Programs & Examples On #Y combinator

The Y combinator is a higher-order function that allows a function that does not know its own name to call itself. It is the fundamental basis of recursion.

What is a Y-combinator?

A Y-combinator is a "functional" (a function that operates on other functions) that enables recursion, when you can't refer to the function from within itself. In computer-science theory, it generalizes recursion, abstracting its implementation, and thereby separating it from the actual work of the function in question. The benefit of not needing a compile-time name for the recursive function is sort of a bonus. =)

This is applicable in languages that support lambda functions. The expression-based nature of lambdas usually means that they cannot refer to themselves by name. And working around this by way of declaring the variable, refering to it, then assigning the lambda to it, to complete the self-reference loop, is brittle. The lambda variable can be copied, and the original variable re-assigned, which breaks the self-reference.

Y-combinators are cumbersome to implement, and often to use, in static-typed languages (which procedural languages often are), because usually typing restrictions require the number of arguments for the function in question to be known at compile time. This means that a y-combinator must be written for any argument count that one needs to use.

Below is an example of how the usage and working of a Y-Combinator, in C#.

Using a Y-combinator involves an "unusual" way of constructing a recursive function. First you must write your function as a piece of code that calls a pre-existing function, rather than itself:

// Factorial, if func does the same thing as this bit of code...
x == 0 ? 1: x * func(x - 1);

Then you turn that into a function that takes a function to call, and returns a function that does so. This is called a functional, because it takes one function, and performs an operation with it that results in another function.

// A function that creates a factorial, but only if you pass in
// a function that does what the inner function is doing.
Func<Func<Double, Double>, Func<Double, Double>> fact =
  (recurs) =>
    (x) =>
      x == 0 ? 1 : x * recurs(x - 1);

Now you have a function that takes a function, and returns another function that sort of looks like a factorial, but instead of calling itself, it calls the argument passed into the outer function. How do you make this the factorial? Pass the inner function to itself. The Y-Combinator does that, by being a function with a permanent name, which can introduce the recursion.

// One-argument Y-Combinator.
public static Func<T, TResult> Y<T, TResult>(Func<Func<T, TResult>, Func<T, TResult>> F)
{
  return
    t =>  // A function that...
      F(  // Calls the factorial creator, passing in...
        Y(F)  // The result of this same Y-combinator function call...
              // (Here is where the recursion is introduced.)
        )
      (t); // And passes the argument into the work function.
}

Rather than the factorial calling itself, what happens is that the factorial calls the factorial generator (returned by the recursive call to Y-Combinator). And depending on the current value of t the function returned from the generator will either call the generator again, with t - 1, or just return 1, terminating the recursion.

It's complicated and cryptic, but it all shakes out at run-time, and the key to its working is "deferred execution", and the breaking up of the recursion to span two functions. The inner F is passed as an argument, to be called in the next iteration, only if necessary.

Javascript objects: get parent

This is an old question but as I came across it looking for an answer I thought I will add my answer to this to help others as soon as they got the same problem.

I have a structure like this:

var structure = {
    "root":{
        "name":"Main Level",
        nodes:{
            "node1":{
                "name":"Node 1"  
            },
            "node2":{
                "name":"Node 2"  
            },
            "node3":{
                "name":"Node 3"  
            }
        }
    }
}

Currently, by referencing one of the sub nodes I don't know how to get the parent node with it's name value "Main Level".

Now I introduce a recursive function that travels the structure and adds a parent attribute to each node object and fills it with its parent like so.

var setParent = function(o){
     if(o.nodes != undefined){
          for(n in o.nodes){
              o.nodes[n].parent = o;
              setParent(o.nodes[n]);
          }
     }
}

Then I just call that function and can now get the parent of the current node in this object tree.

setParent(structure.root);

If I now have a reference to the seconds sub node of root, I can just call.

var node2 = structure.root.nodes["node2"];
console.log(node2.parent.name);

and it will output "Main Level".

Hope this helps..

Passing in class names to react components

Just for the reference, for stateless components:

// ParentComponent.js
import React from 'react';
import { ChildComponent } from '../child/ChildComponent';

export const ParentComponent = () =>
  <div className="parent-component">
    <ChildComponent className="parent-component__child">
      ...
    </ChildComponent>
  </div>

// ChildComponent.js
import React from 'react';

export const ChildComponent = ({ className, children }) =>
  <div className={`some-css-className ${className}`}>
    {children}
  </div>

Will render:

<div class="parent-component">
  <div class="some-css-className parent-component__child">
    ...
  </div>
</div>

Nginx 403 forbidden for all files

I solved this problem by adding user settings.

in nginx.conf

worker_processes 4;
user username;

change the 'username' with linux user name.

What is the best or most commonly used JMX Console / Client

Alternatively, constructing a JMX console yourself doesn't need to be hard. Just plug in Jolokia and create a web page getting the attributes that you're interested in. Admittedly, it doesn't allow you to do trend analysis, but it does allow you to construct something that is really geared towards your purpose.

I constructed something in just a few lines: http://nxt.flotsam.nl/ears-and-eyes.html

Get Enum from Description attribute

Should be pretty straightforward, its just the reverse of your previous method;

public static int GetEnumFromDescription(string description, Type enumType)
{
    foreach (var field in enumType.GetFields())
    {
        DescriptionAttribute attribute
            = Attribute.GetCustomAttribute(field, typeof(DescriptionAttribute))as DescriptionAttribute;
        if(attribute == null)
            continue;
        if(attribute.Description == description)
        {
            return (int) field.GetValue(null);
        }
    }
    return 0;
}

Usage:

Console.WriteLine((Animal)GetEnumFromDescription("Giant Panda",typeof(Animal)));

pdftk compression option

If file size is still too large it could help using ps2pdf to downscale the resolution of the produced pdf file:

pdf2ps input.pdf tmp.ps
ps2pdf -dPDFSETTINGS=/screen -dDownsampleColorImages=true -dColorImageResolution=200 -dColorImageDownsampleType=/Bicubic tmp.ps output.pdf

Adjust the value of the -dColorImageResolution option to achieve a result that fits your needs (the value describes the image resolution in DPIs). If your input file is in grayscale, replacing Color through Gray or using both options in the above command could also help. Further fine-tuning is possible by changing the -dPDFSETTINGS option to /default or /printer. For explanations of the all possible options consult the ps2pdf manual.

Spring Could not Resolve placeholder

For properties that need to be managed outside of the WAR:

<context:property-placeholder location="file:///C:/application.yml"/>

For example if inside application.yml are name and id

Then you can create bean in runtime inside xml spring

<bean id="id1" class="my.class.Item">
    <property name="name" value="${name}"/>
    <property name="id" value="${id}"/>
</bean>

Angular: date filter adds timezone, how to output UTC?

The 'Z' is what adds the timezone info. As for output UTC, that seems to be the subject of some confusion -- people seem to gravitate toward moment.js.

Borrowing from this answer, you could do something like this without moment.js:

controller

var app1 = angular.module('app1',[]);

app1.controller('ctrl',['$scope',function($scope){

  var toUTCDate = function(date){
    var _utc = new Date(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(),  date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds());
    return _utc;
  };

  var millisToUTCDate = function(millis){
    return toUTCDate(new Date(millis));
  };

    $scope.toUTCDate = toUTCDate;
    $scope.millisToUTCDate = millisToUTCDate;

  }]);

template

<html ng-app="app1">

  <head>
    <script data-require="angular.js@*" data-semver="1.2.12" src="http://code.angularjs.org/1.2.12/angular.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
  </head>

  <body>
    <div ng-controller="ctrl">
      <div>
      utc {{millisToUTCDate(1400167800) | date:'dd-M-yyyy H:mm'}}
      </div>
      <div>
      local {{1400167800 | date:'dd-M-yyyy H:mm'}}
      </div>
    </div>
  </body>

</html>

here's plunker to play with it

See also this and this.

Also note that with this method, if you use the 'Z' from Angular's date filter, it seems it will still print your local timezone offset.

How to print all information from an HTTP request to the screen, in PHP

A simple way would be:

<?php
print_r($_SERVER);
print_r($_POST);
print_r($_GET);
print_r($_FILES);
?>

A bit of massaging would be required to get everything in the order you want, and to exclude the variables you are not interested in, but should give you a start.

How to initialize a vector of vectors on a struct?

You use new to perform dynamic allocation. It returns a pointer that points to the dynamically allocated object.

You have no reason to use new, since A is an automatic variable. You can simply initialise A using its constructor:

vector<vector<int> > A(dimension, vector<int>(dimension));

Is it possible to append Series to rows of DataFrame without making a list first?

Try using this command. See the example given below:

Before image

df.loc[len(df)] = ['Product 9',99,9.99,8.88,1.11]

df

After Image

How to iterate through a DataTable

There are already nice solution has been given. The below code can help others to query over datatable and get the value of each row of the datatable for the ImagePath column.

  for (int i = 0; i < dataTable.Rows.Count; i++)
  {
       var theUrl = dataTable.Rows[i]["ImagePath"].ToString();
  }

How can I use PHP to dynamically publish an ical file to be read by Google Calendar?

Make sure you format the string like this or it wont work

 $content = "BEGIN:VCALENDAR\n".
            "VERSION:2.0\n".
            "PRODID:-//hacksw/handcal//NONSGML v1.0//EN\n".
            "BEGIN:VEVENT\n".
            "UID:".uniqid()."\n".
            "DTSTAMP:".$time."\n".
            "DTSTART:".$time."\n".
            "DTEND:".$time."\n".
            "SUMMARY:".$summary."\n".
            "END:VEVENT\n".
            "END:VCALENDAR";

How to study design patterns?

Have you read "Design Patterns Explained", by Allan Shalloway.

This book is very different from other design pattern books because it is not so much a catalog of patterns, but primarily presents a way of decomposing a problem space that maps easily to patterns.

Problems can be decomposed into two parts: things that are common and things that vary. Once this is done, we map the common things to an interface, and the things that vary to an implementation. In essence, many patterns fall into this "pattern".

For example in the Strategy pattern, the common things are expressed as the strategy's context, and the variable parts are expressed as the concrete strategies.

I found this book highly thought provoking in contrast with other pattern books which, for me, have the same degree of excitement as reading a phone book.

How do I subscribe to all topics of a MQTT broker

You can use mosquitto_sub (which is part of the mosquitto-clients package) and subscribe to the wildcard topic #:

mosquitto_sub -v -h broker_ip -p 1883 -t '#'

How to open in default browser in C#

public static void GoToSite(string url)
{
     System.Diagnostics.Process.Start(url);
}

that should solve your problem

How to convert minutes to Hours and minutes (hh:mm) in java

I use this function for my projects:

 public static String minuteToTime(int minute) {
    int hour = minute / 60;
    minute %= 60;
    String p = "AM";
    if (hour >= 12) {
        hour %= 12;
        p = "PM";
    }
    if (hour == 0) {
        hour = 12;
    }
    return (hour < 10 ? "0" + hour : hour) + ":" + (minute < 10 ? "0" + minute : minute) + " " + p;
}

Matlab: Running an m-file from command-line

I think that one important point that was not mentioned in the previous answers is that, if not explicitly indicated, the matlab interpreter will remain open. Therefore, to the answer of @hkBattousai I will add the exit command:

"C:\<a long path here>\matlab.exe" -nodisplay -nosplash -nodesktop -r "run('C:\<a long path here>\mfile.m');exit;"

Check if string contains a value in array

Try this.

$string = 'my domain name is website3.com';
foreach ($owned_urls as $url) {
    //if (strstr($string, $url)) { // mine version
    if (strpos($string, $url) !== FALSE) { // Yoshi version
        echo "Match found"; 
        return true;
    }
}
echo "Not found!";
return false;

Use stristr() or stripos() if you want to check case-insensitive.

Dynamic classname inside ngClass in angular 2

Try

<button [ngClass]="type === 'mybutton' ? namespace + '-mybutton' : ''"></button>

instead.

or

<button [ngClass]="[type === 'mybutton' ? namespace + '-mybutton' : '']"></button>

or even

<button class="{{type === 'mybutton' ? namespace + '-mybutton' : ''}}"></button>

will work but extra benefit of using ngClass is that it does not overwrite other classes that are added by any other method( eg: [class.xyz] directive or class attribute, etc.) as class does.

Angular 9 Update

The new compiler, Ivy, brings more clarity and predictability to what happens when there are different types of class-bindings on the same element. Read More about it here.


ngClass takes three types of input

  • Object: each key corresponds to a CSS class name, you can't have dynamic keys, because key 'key' "key" are all same, and [key] is not supported AFAIK.
  • Array: can only contain list of classes, no conditions, although ternary operator works
  • String/ expression: just like normal class attribute

PowerMockito mock single static method and return object

What you want to do is a combination of part of 1 and all of 2.

You need to use the PowerMockito.mockStatic to enable static mocking for all static methods of a class. This means make it possible to stub them using the when-thenReturn syntax.

But the 2-argument overload of mockStatic you are using supplies a default strategy for what Mockito/PowerMock should do when you call a method you haven't explicitly stubbed on the mock instance.

From the javadoc:

Creates class mock with a specified strategy for its answers to interactions. It's quite advanced feature and typically you don't need it to write decent tests. However it can be helpful when working with legacy systems. It is the default answer so it will be used only when you don't stub the method call.

The default default stubbing strategy is to just return null, 0 or false for object, number and boolean valued methods. By using the 2-arg overload, you're saying "No, no, no, by default use this Answer subclass' answer method to get a default value. It returns a Long, so if you have static methods which return something incompatible with Long, there is a problem.

Instead, use the 1-arg version of mockStatic to enable stubbing of static methods, then use when-thenReturn to specify what to do for a particular method. For example:

import static org.mockito.Mockito.*;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

class ClassWithStatics {
  public static String getString() {
    return "String";
  }

  public static int getInt() {
    return 1;
  }
}

@RunWith(PowerMockRunner.class)
@PrepareForTest(ClassWithStatics.class)
public class StubJustOneStatic {
  @Test
  public void test() {
    PowerMockito.mockStatic(ClassWithStatics.class);

    when(ClassWithStatics.getString()).thenReturn("Hello!");

    System.out.println("String: " + ClassWithStatics.getString());
    System.out.println("Int: " + ClassWithStatics.getInt());
  }
}

The String-valued static method is stubbed to return "Hello!", while the int-valued static method uses the default stubbing, returning 0.

How to change resolution (DPI) of an image?

It's simply a matter of scaling the image width and height up by the correct ratio. Not all images formats support a DPI metatag, and when they do, all they're telling your graphics software to do is divide the image by the ratio supplied.

For example, if you export a 300dpi image from Photoshop to a JPEG, the image will appear to be very large when viewed in your picture viewing software. This is because the DPI information isn't supported in JPEG and is discarded when saved. This means your picture viewer doesn't know what ratio to divide the image by and instead displays the image at at 1:1 ratio.

To get the ratio you need to scale the image by, see the code below. Just remember, this will stretch the image, just like it would in Photoshop. You're essentially quadrupling the size of the image so it's going to stretch and may produce artifacts.

Pseudo code

ratio = 300.0 / 72.0   // 4.167
image.width * ratio
image.height * ratio

Change working directory in my current shell context when running Node script

What you are trying to do is not possible. The reason for this is that in a POSIX system (Linux, OSX, etc), a child process cannot modify the environment of a parent process. This includes modifying the parent process's working directory and environment variables.

When you are on the commandline and you go to execute your Node script, your current process (bash, zsh, whatever) spawns a new process which has it's own environment, typically a copy of your current environment (it is possible to change this via system calls; but that's beyond the scope of this reply), allowing that process to do whatever it needs to do in complete isolation. When the subprocess exits, control is handed back to your shell's process, where the environment hasn't been affected.

There are a lot of reasons for this, but for one, imagine that you executed a script in the background (via ./foo.js &) and as it ran, it started changing your working directory or overriding your PATH. That would be a nightmare.

If you need to perform some actions that require changing your working directory of your shell, you'll need to write a function in your shell. For example, if you're running Bash, you could put this in your ~/.bash_profile:

do_cool_thing() {
  cd "/Users"
  echo "Hey, I'm in $PWD"
}

and then this cool thing is doable:

$ pwd
/Users/spike
$ do_cool_thing
Hey, I'm in /Users
$ pwd
/Users

If you need to do more complex things in addition, you could always call out to your nodejs script from that function.

This is the only way you can accomplish what you're trying to do.

How can I get the baseurl of site?

Please use the below code                           

string.Format("{0}://{1}", Request.url.Scheme, Request.url.Host);

Check if a value is an object in JavaScript

You can do this easily with toString() method of Object.prototype

if(Object.prototype.toString.call(variable) == "[object Object]"){
   doSomething();
}

or

if(Object.prototype.toString.call(variable).slice(8,-1).toLowerCase() == "object"){
   doSomething();
}

Convert canvas to PDF

A better solution would be using Kendo ui draw dom to export to pdf-

Suppose the following html file which contains the canvas tag:

<script src="http://kendo.cdn.telerik.com/2017.2.621/js/kendo.all.min.js"></script>

    <script type="x/kendo-template" id="page-template">
     <div class="page-template">
            <div class="header">

            </div>
            <div class="footer" style="text-align: center">

                <h2> #:pageNum# </h2>
            </div>
      </div>
    </script>
    <canvas id="myCanvas" width="500" height="500"></canvas>
    <button onclick="ExportPdf()">download</button>

Now after that in your script write down the following and it will be done:

function ExportPdf(){ 
kendo.drawing
    .drawDOM("#myCanvas", 
    { 
        forcePageBreak: ".page-break", 
        paperSize: "A4",
        margin: { top: "1cm", bottom: "1cm" },
        scale: 0.8,
        height: 500, 
        template: $("#page-template").html(),
        keepTogether: ".prevent-split"
    })
        .then(function(group){
        kendo.drawing.pdf.saveAs(group, "Exported_Itinerary.pdf")
    });
}

And that is it, Write anything in that canvas and simply press that download button all exported into PDF. Here is a link to Kendo UI - http://docs.telerik.com/kendo-ui/framework/drawing/drawing-dom And a blog to better understand the whole process - https://www.cronj.com/blog/export-htmlcss-pdf-using-javascript/

C++ preprocessor __VA_ARGS__ number of arguments

herein a simple way to count 0 or more arguments of VA_ARGS, my exemple assumes a maximum of 5 variables, but you can add more if you want.

#define VA_ARGS_NUM_PRIV(P1, P2, P3, P4, P5, P6, Pn, ...) Pn
#define VA_ARGS_NUM(...) VA_ARGS_NUM_PRIV(-1, ##__VA_ARGS__, 5, 4, 3, 2, 1, 0)


VA_ARGS_NUM()      ==> 0
VA_ARGS_NUM(19)    ==> 1
VA_ARGS_NUM(9, 10) ==> 2
         ...

How to add a line break within echo in PHP?

You have to use br when using echo , like this :

echo "Thanks for your email" ."<br>". "Your orders details are below:"

and it will work properly

Sorting an ArrayList of objects using a custom sorting order

By using lambdaj you can sort a collection of your contacts (for example by their name) as it follows

sort(contacts, on(Contact.class).getName());

or by their address:

sort(contacts, on(Contacts.class).getAddress());

and so on. More in general, it offers a DSL to access and manipulate your collections in many ways, like filtering or grouping your contacts based on some conditions, aggregate some of their property values, etc.

remove objects from array by object property

Only native JavaScript please.

As an alternative, more "functional" solution, working on ECMAScript 5, you could use:

var listToDelete = ['abc', 'efg'];
var arrayOfObjects = [{id:'abc',name:'oh'}, // delete me
                      {id:'efg',name:'em'}, // delete me
                      {id:'hij',name:'ge'}]; // all that should remain

arrayOfObjects.reduceRight(function(acc, obj, idx) {
    if (listToDelete.indexOf(obj.id) > -1)
        arrayOfObjects.splice(idx,1);
}, 0); // initial value set to avoid issues with the first item and
       // when the array is empty.

console.log(arrayOfObjects);
[ { id: 'hij', name: 'ge' } ]

According to the definition of 'Array.prototype.reduceRight' in ECMA-262:

reduceRight does not directly mutate the object on which it is called but the object may be mutated by the calls to callbackfn.

So this is a valid usage of reduceRight.

PHP7 : install ext-dom issue

For whom want to install ext-dom on php 7.1 and up run this command:

sudo apt install php-xml

Outline radius?

There is the solution if you need only outline without border. It's not mine. I got if from Bootstrap css file. If you specify outline: 1px auto certain_color, you'll get thin outer line around div of certain color. In this case the specified width has no matter, even if you specify 10 px width, anyway it will be thin line. The key word in mentioned rule is "auto".
If you need outline with rounded corners and certain width, you may add css rule on border with needed width and same color. It makes outline thicker.

What is the difference between IQueryable<T> and IEnumerable<T>?

IQueryable is faster than IEnumerable if we are dealing with huge amounts of data from database because,IQueryable gets only required data from database where as IEnumerable gets all the data regardless of the necessity from the database

How to download file in swift?

Devran's and djunod's solutions are working as long as your application is in the foreground. If you switch to another application during the download, it fails. My file sizes are around 10 MB and it takes sometime to download. So I need my download function works even when the app goes into background.

Please note that I switched ON the "Background Modes / Background Fetch" at "Capabilities".

Since completionhandler was not supported the solution is not encapsulated. Sorry about that.

--Swift 2.3--

import Foundation 
class Downloader : NSObject, NSURLSessionDownloadDelegate
{
    var url : NSURL? 
    // will be used to do whatever is needed once download is complete
    var yourOwnObject : NSObject?

    init(yourOwnObject : NSObject)
    {
        self.yourOwnObject = yourOwnObject
    }

    //is called once the download is complete
    func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL)
    {
        //copy downloaded data to your documents directory with same names as source file
        let documentsUrl =  NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first
        let destinationUrl = documentsUrl!.URLByAppendingPathComponent(url!.lastPathComponent!)
        let dataFromURL = NSData(contentsOfURL: location)
        dataFromURL?.writeToURL(destinationUrl, atomically: true)

        //now it is time to do what is needed to be done after the download
        yourOwnObject!.callWhatIsNeeded()
    }

    //this is to track progress
    func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64)
    {
    }

    // if there is an error during download this will be called
    func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?)
    {
        if(error != nil)
        {
            //handle the error
            print("Download completed with error: \(error!.localizedDescription)");
        }
    }

    //method to be called to download
    func download(url: NSURL)
    {
        self.url = url

        //download identifier can be customized. I used the "ulr.absoluteString"
        let sessionConfig = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(url.absoluteString)
        let session = NSURLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
        let task = session.downloadTaskWithURL(url)
        task.resume()
    }
}

And here is how to call in --Swift 2.3--

    let url = NSURL(string: "http://company.com/file.txt")
    Downloader(yourOwnObject).download(url!)

--Swift 3--

class Downloader : NSObject, URLSessionDownloadDelegate {

var url : URL?
// will be used to do whatever is needed once download is complete
var yourOwnObject : NSObject?

init(_ yourOwnObject : NSObject)
{
    self.yourOwnObject = yourOwnObject
}

//is called once the download is complete
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL)
{
    //copy downloaded data to your documents directory with same names as source file
    let documentsUrl =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
    let destinationUrl = documentsUrl!.appendingPathComponent(url!.lastPathComponent)
    let dataFromURL = NSData(contentsOf: location)
    dataFromURL?.write(to: destinationUrl, atomically: true)

    //now it is time to do what is needed to be done after the download
    yourOwnObject!.callWhatIsNeeded()
}

//this is to track progress
private func URLSession(session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64)
{
}

// if there is an error during download this will be called
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?)
{
    if(error != nil)
    {
        //handle the error
        print("Download completed with error: \(error!.localizedDescription)");
    }
}

//method to be called to download
func download(url: URL)
{
    self.url = url

    //download identifier can be customized. I used the "ulr.absoluteString"
    let sessionConfig = URLSessionConfiguration.background(withIdentifier: url.absoluteString)
    let session = Foundation.URLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
    let task = session.downloadTask(with: url)
    task.resume()
}}

And here is how to call in --Swift 3--

    let url = URL(string: "http://company.com/file.txt")
    Downloader(yourOwnObject).download(url!)

How to convert image file data in a byte array to a Bitmap?

Just try this:

Bitmap bitmap = BitmapFactory.decodeFile("/path/images/image.jpg");
ByteArrayOutputStream blob = new ByteArrayOutputStream();
bitmap.compress(CompressFormat.PNG, 0 /* Ignored for PNGs */, blob);
byte[] bitmapdata = blob.toByteArray();

If bitmapdata is the byte array then getting Bitmap is done like this:

Bitmap bitmap = BitmapFactory.decodeByteArray(bitmapdata, 0, bitmapdata.length);

Returns the decoded Bitmap, or null if the image could not be decoded.

Bootstrap 3 breakpoints and media queries

This issue has been discussed in https://github.com/twbs/bootstrap/issues/10203 By now, there is no plan to change Grid because compatibility reasons.

You can get Bootstrap from this fork, branch hs: https://github.com/antespi/bootstrap/tree/hs

This branch give you an extra breakpoint at 480px, so yo have to:

  1. Design for mobile first (XS, less than 480px)
  2. Add HS (Horizontal Small Devices) classes in your HTML: col-hs-*, visible-hs, ... and design for horizontal mobile devices (HS, less than 768px)
  3. Design for tablet devices (SM, less than 992px)
  4. Design for desktop devices (MD, less than 1200px)
  5. Design for large devices (LG, more than 1200px)

Design mobile first is the key to understand Bootstrap 3. This is the major change from BootStrap 2.x. As a rule template you can follow this (in LESS):

.template {
    /* rules for mobile vertical (< 480) */

    @media (min-width: @screen-hs-min) {
       /* rules for mobile horizontal (480 > 768)  */
    }
    @media (min-width: @screen-sm-min) {
       /* rules for tablet (768 > 992) */
    }
    @media (min-width: @screen-md-min) {
       /* rules for desktop (992 > 1200) */
    }
    @media (min-width: @screen-lg-min) {
       /* rules for large (> 1200) */
    }
}

java.util.MissingResourceException: Can't find bundle for base name 'property_file name', locale en_US

just right click on the project file in eclipse and in build path select "Use as source folder"...It worked for me

mysql - move rows from one table to another

To move and delete specific records by selecting using WHERE query,

BEGIN TRANSACTION;
Insert Into A SELECT * FROM B where URL="" AND email ="" AND Annual_Sales_Vol="" And OPENED_In="" AND emp_count=""  And contact_person= "" limit 0,2000;
delete from B where Id In (select Id from B where URL="" AND email ="" AND Annual_Sales_Vol="" And OPENED_In="" AND emp_count="" And contact_person= "" limit 0,2000);
commit;

Could not load file or assembly ... The parameter is incorrect

I had users of Siemens Teamcenter 10 Client for Microsoft Office getting the same error about a different DLL. None of the other answers worked. The solution was to delete the folders in

C:\Users\%username%\AppData\Local\assembly\

How to fix Error: laravel.log could not be opened?

You could do:

chcon -R -t httpd_sys_rw_content_t storage

jQuery function to get all unique elements from an array?

Based on @kennebec's answer, but fixed for IE8 and below by using jQuery wrappers around the array to provide missing Array functions filter and indexOf:

$.makeArray() wrapper might not be absolutely needed, but you'll get odd results if you omit this wrapper and JSON.stringify the result otherwise.

var a = [1,5,1,6,4,5,2,5,4,3,1,2,6,6,3,3,2,4];

// note: jQuery's filter params are opposite of javascript's native implementation :(
var unique = $.makeArray($(a).filter(function(i,itm){ 
    // note: 'index', not 'indexOf'
    return i == $(a).index(itm);
}));

// unique: [1, 5, 6, 4, 2, 3]

what's the differences between r and rb in fopen

You should use "r" for opening text files. Different operating systems have slightly different ways of storing text, and this will perform the correct translations so that you don't need to know about the idiosyncracies of the local operating system. For example, you will know that newlines will always appear as a simple "\n", regardless of where the code runs.

You should use "rb" if you're opening non-text files, because in this case, the translations are not appropriate.

How to create an Explorer-like folder browser control?

Take a look at Shell MegaPack control set. It provides Windows Explorer like folder/file browsing with most of the features and functionality like context menus, renaming, drag-drop, icons, overlay icons, thumbnails, etc

catch forEach last iteration

const arr= [1, 2, 3]
arr.forEach(function(element){
 if(arr[arr.length-1] === element){
  console.log("Last Element")
 }
})

Find all files with a filename beginning with a specified string?

Use find with a wildcard:

find . -name 'mystring*'

Visual Studio 2015 is very slow

Try uninstalling either Node.js Tools for Visual Studio (NTVS) or the commercial add-on called ReSharper from JetBrains. Using both NTVS and Resharper causes memory leaks in Visual Studio 2015.

NTVS = Node Tools for Visual Studio

How to set top-left alignment for UILabel for iOS application?

As you are using the interface builder, set the constraints for your label (be sure to set the height and width as well). Then in the Size Inspector, check the height for the label. There you will want it to read >= instead of =. Then in the implementation for that view controller, set the number of lines to 0 (can also be done in IB) and set the label [label sizeToFit]; and as your text gains length, the label will grow in height and keep your text in the upper left.

Classpath including JAR within a JAR

If you're trying to create a single jar that contains your application and its required libraries, there are two ways (that I know of) to do that. The first is One-Jar, which uses a special classloader to allow the nesting of jars. The second is UberJar, (or Shade), which explodes the included libraries and puts all the classes in the top-level jar.

I should also mention that UberJar and Shade are plugins for Maven1 and Maven2 respectively. As mentioned below, you can also use the assembly plugin (which in reality is much more powerful, but much harder to properly configure).

Is it possible to disable floating headers in UITableView with UITableViewStylePlain?

Ok, i know it is late but i had to do it. I have spent 10 hours by now searching for a working solution but did not find a complete answer. Did found some hints but difficult for starters to understand. So i had to put in my 2 cents and complete the answer.

As it has been suggested in the few of the answers the only working solution that i was able to implement is by inserting normal cells in the table view and handle them as Section Headers, but the better way to achieve it is by inserting these cells at row 0 of every section. This way we can handle these custom non-floating headers very easily.

So, the steps are.

  1. Implement UITableView with style UITableViewStylePlain.

    -(void) loadView
    {
        [super loadView];
    
        UITableView *tblView =[[UITableView alloc] initWithFrame:CGRectMake(0, frame.origin.y, frame.size.width, frame.size.height-44-61-frame.origin.y) style:UITableViewStylePlain];
        tblView.delegate=self;
        tblView.dataSource=self;
        tblView.tag=2;
        tblView.backgroundColor=[UIColor clearColor];
        tblView.separatorStyle = UITableViewCellSeparatorStyleNone;
    }
    
  2. Implement titleForHeaderInSection as usual ( you can get this value by using your own logic, but I prefer to use standard delegates ).

    - (NSString *)tableView: (UITableView *)tableView titleForHeaderInSection:(NSInteger)section
    {
        NSString *headerTitle = [sectionArray objectAtIndex:section];
        return headerTitle;
    }
    
  3. Immplement numberOfSectionsInTableView as usual

    - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
    {
        int sectionCount = [sectionArray count];
        return sectionCount;
    }
    
  4. Implement numberOfRowsInSection as usual.

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
    {
        int rowCount = [[cellArray objectAtIndex:section] count];
        return rowCount +1; //+1 for the extra row which we will fake for the Section Header
    }
    
  5. Return 0.0f in heightForHeaderInSection.

    - (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
    {
        return 0.0f;
    }
    
  6. DO NOT implement viewForHeaderInSection. Remove the method completely instead of returning nil.

  7. In heightForRowAtIndexPath. Check if(indexpath.row == 0) and return the desired cell height for the section header, else return the height of the cell.

    - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if(indexPath.row == 0)
        {
            return 80; //Height for the section header
        }
        else
        {
            return 70; //Height for the normal cell
        }
    }
    
  8. Now in cellForRowAtIndexPath, check if(indexpath.row == 0) and implement the cell as you want the section header to be and set the selection style to none. ELSE implement the cell as you want the normal cell to be.

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if (indexPath.row == 0)
        {
            UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"SectionCell"];
            if (cell == nil)
            {
                cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"SectionCell"] autorelease];
                cell.selectionStyle = UITableViewCellSelectionStyleNone; //So that the section header does not appear selected
    
                cell.backgroundView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"SectionHeaderBackground"]];
            }
    
            cell.textLabel.text = [tableView.dataSource tableView:tableView titleForHeaderInSection:indexPath.section];
    
            return cell;
        }
        else
        {
            UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
    
            if (cell == nil) 
            {
                cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"] autorelease];
                cell.selectionStyle = UITableViewCellSelectionStyleGray; //So that the normal cell looks selected
    
                cell.backgroundView =[[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"CellBackground"]]autorelease];
                cell.selectedBackgroundView=[[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"SelectedCellBackground"]] autorelease];
            }
    
            cell.textLabel.text = [[cellArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row -1]; //row -1 to compensate for the extra header row
    
            return cell;
        }
    }
    
  9. Now implement willSelectRowAtIndexPath and return nil if indexpath.row == 0. This will care that didSelectRowAtIndexPath never gets fired for the Section header row.

    - (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if (indexPath.row == 0)
        {
            return nil;
        }
    
        return indexPath;
    }
    
  10. And finally in didSelectRowAtIndexPath, check if(indexpath.row != 0) and proceed.

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    {
        if (indexPath.row != 0)
        {
            int row = indexPath.row -1; //Now use 'row' in place of indexPath.row
    
            //Do what ever you want the selection to perform
        }
    }
    

With this you are done. You now have a perfectly scrolling, non-floating section header.

How to use regex in XPath "contains" function

XPath 1.0 doesn't handle regex natively, you could try something like

//*[starts-with(@id, 'sometext') and ends-with(@id, '_text')]

(as pointed out by paul t, //*[boolean(number(substring-before(substring-after(@id, "sometext"), "_text")))] could be used to perform the same check your original regex does, if you need to check for middle digits as well)

In XPath 2.0, try

//*[matches(@id, 'sometext\d+_text')]

How can I disable HREF if onclick is executed?

<a href="http://www.google.com" class="ignore-click">Test</a>

with jQuery:

<script>
    $(".ignore-click").click(function(){
        return false;
    })
</script>

with JavaScript

<script>
        for (var i = 0; i < document.getElementsByClassName("ignore-click").length; i++) {
            document.getElementsByClassName("ignore-click")[i].addEventListener('click', function (event) {
                event.preventDefault();
                return false;
            });
        }
</script>

You assign class .ignore-click to as many elements you like and clicks on those elements will be ignored

How to sort a collection by date in MongoDB?

Additional Square [ ] Bracket is required for sorting parameter to work.

collection.find({}, {"sort" : [['datefield', 'asc']]} ).toArray(function(err,docs) {});

Express-js can't GET my static files, why?

I have the same problem. I have resolved the problem with following code:

app.use('/img',express.static(path.join(__dirname, 'public/images')));
app.use('/js',express.static(path.join(__dirname, 'public/javascripts')));
app.use('/css',express.static(path.join(__dirname, 'public/stylesheets')));

Static request example:

http://pruebaexpress.lite.c9.io/js/socket.io.js

I need a more simple solution. Does it exist?

"/usr/bin/ld: cannot find -lz"

Others have mentioned that lib32z-dev solves the problem, but in general the required packages can be found here:

http://source.android.com/source/initializing.html See "Installing required packages"

Obtaining only the filename when using OpenFileDialog property "FileName"

Use: Path.GetFileName Method

var onlyFileName = System.IO.Path.GetFileName(ofd.FileName);

What is the "right" JSON date format?

JSON itself does not specify how dates should be represented, but JavaScript does.

You should use the format emitted by Date's toJSON method:

2012-04-23T18:25:43.511Z

Here's why:

  1. It's human readable but also succinct

  2. It sorts correctly

  3. It includes fractional seconds, which can help re-establish chronology

  4. It conforms to ISO 8601

  5. ISO 8601 has been well-established internationally for more than a decade

  6. ISO 8601 is endorsed by W3C, RFC3339, and XKCD

That being said, every date library ever written can understand "milliseconds since 1970". So for easy portability, ThiefMaster is right.

Fixed point vs Floating point number

A fixed point number has a specific number of bits (or digits) reserved for the integer part (the part to the left of the decimal point) and a specific number of bits reserved for the fractional part (the part to the right of the decimal point). No matter how large or small your number is, it will always use the same number of bits for each portion. For example, if your fixed point format was in decimal IIIII.FFFFF then the largest number you could represent would be 99999.99999 and the smallest non-zero number would be 00000.00001. Every bit of code that processes such numbers has to have built-in knowledge of where the decimal point is.

A floating point number does not reserve a specific number of bits for the integer part or the fractional part. Instead it reserves a certain number of bits for the number (called the mantissa or significand) and a certain number of bits to say where within that number the decimal place sits (called the exponent). So a floating point number that took up 10 digits with 2 digits reserved for the exponent might represent a largest value of 9.9999999e+50 and a smallest non-zero value of 0.0000001e-49.

Android Relative Layout Align Center

If you want to make it center then use android:layout_centerVertical="true" in the TextView.

What generates the "text file busy" message in Unix?

In my case, I was trying to execute a shell file (with an extension .sh) in a csh environment, and I was getting that error message.

just running with bash it worked for me. For example

bash file.sh

How can I URL encode a string in Excel VBA?

Same as WorksheetFunction.EncodeUrl with UTF-8 support:

Public Function EncodeURL(url As String) As String
  Dim buffer As String, i As Long, c As Long, n As Long
  buffer = String$(Len(url) * 12, "%")

  For i = 1 To Len(url)
    c = AscW(Mid$(url, i, 1)) And 65535

    Select Case c
      Case 48 To 57, 65 To 90, 97 To 122, 45, 46, 95  ' Unescaped 0-9A-Za-z-._ '
        n = n + 1
        Mid$(buffer, n) = ChrW(c)
      Case Is <= 127            ' Escaped UTF-8 1 bytes U+0000 to U+007F '
        n = n + 3
        Mid$(buffer, n - 1) = Right$(Hex$(256 + c), 2)
      Case Is <= 2047           ' Escaped UTF-8 2 bytes U+0080 to U+07FF '
        n = n + 6
        Mid$(buffer, n - 4) = Hex$(192 + (c \ 64))
        Mid$(buffer, n - 1) = Hex$(128 + (c Mod 64))
      Case 55296 To 57343       ' Escaped UTF-8 4 bytes U+010000 to U+10FFFF '
        i = i + 1
        c = 65536 + (c Mod 1024) * 1024 + (AscW(Mid$(url, i, 1)) And 1023)
        n = n + 12
        Mid$(buffer, n - 10) = Hex$(240 + (c \ 262144))
        Mid$(buffer, n - 7) = Hex$(128 + ((c \ 4096) Mod 64))
        Mid$(buffer, n - 4) = Hex$(128 + ((c \ 64) Mod 64))
        Mid$(buffer, n - 1) = Hex$(128 + (c Mod 64))
      Case Else                 ' Escaped UTF-8 3 bytes U+0800 to U+FFFF '
        n = n + 9
        Mid$(buffer, n - 7) = Hex$(224 + (c \ 4096))
        Mid$(buffer, n - 4) = Hex$(128 + ((c \ 64) Mod 64))
        Mid$(buffer, n - 1) = Hex$(128 + (c Mod 64))
    End Select
  Next

  EncodeURL = Left$(buffer, n)
End Function

Custom sort function in ng-repeat

To include the direction along with the orderBy function:

ng-repeat="card in cards | orderBy:myOrderbyFunction():defaultSortDirection"

where

defaultSortDirection = 0; // 0 = Ascending, 1 = Descending

How do you beta test an iphone app?

In 2014 along with iOS 8 and XCode 6 apple introduced Beta Testing of iOS App using iTunes Connect.

You can upload your build to iTunes connect and invite testers using their mail id's. You can invite up to 2000 external testers using just their email address. And they can install the beta app through TestFlight

How to redirect to previous page in Ruby On Rails?

request.referer is set by Rack and is set as follows:

def referer
  @env['HTTP_REFERER'] || '/'
end

Just do a redirect_to request.referer and it will always redirect to the true referring page, or the root_path ('/'). This is essential when passing tests that fail in cases of direct-nav to a particular page in which the controller throws a redirect_to :back

load external css file in body tag

No, it is not okay to put a link element in the body tag. See the specification (links to the HTML4.01 specs, but I believe it is true for all versions of HTML):

“This element defines a link. Unlike A, it may only appear in the HEAD section of a document, although it may appear any number of times.”

Celery Received unregistered task of type (run example)

This, strangely, can also be because of a missing package. Run pip to install all necessary packages: pip install -r requirements.txt

autodiscover_tasks wasn't picking up tasks that used missing packages.

How to insert close button in popover for Bootstrap

The trick is to get the current Popover with .data('bs.popover').tip():

$('#my_trigger').popover().on('shown.bs.popover', function() {
    // Define elements
    var current_trigger=$(this);
    var current_popover=current_trigger.data('bs.popover').tip();

    // Activate close button
    current_popover.find('button.close').click(function() {
        current_trigger.popover('hide');
    });
});

Reset C int array to zero : the fastest way?

From memset():

memset(myarray, 0, sizeof(myarray));

You can use sizeof(myarray) if the size of myarray is known at compile-time. Otherwise, if you are using a dynamically-sized array, such as obtained via malloc or new, you will need to keep track of the length.

What is the difference between supervised learning and unsupervised learning?

Supervised learning

Applications in which the training data comprises examples of the input vectors along with their corresponding target vectors are known as supervised learning problems.

Unsupervised learning

In other pattern recognition problems, the training data consists of a set of input vectors x without any corresponding target values. The goal in such unsupervised learning problems may be to discover groups of similar examples within the data, where it is called clustering

Pattern Recognition and Machine Learning (Bishop, 2006)

JavaScript Array to Set

Just pass the array to the Set constructor. The Set constructor accepts an iterable parameter. The Array object implements the iterable protocol, so its a valid parameter.

_x000D_
_x000D_
var arr = [55, 44, 65];_x000D_
var set = new Set(arr);_x000D_
console.log(set.size === arr.length);_x000D_
console.log(set.has(65));
_x000D_
_x000D_
_x000D_

See here

System.Windows.Markup.XamlParseException' occurred in PresentationFramework.dll?

When I had this problem, I had literally just forgot to fill in a parameter value in the XAML of the code.

For some reason though, the exception would send me to the CS of the WPF program rather than the XAML. No idea why.

How do you run a Python script as a service in Windows?

This answer is plagiarizer from several sources on StackOverflow - most of them above, but I've forgotten the others - sorry. It's simple and scripts run "as is". For releases you test you script, then copy it to the server and Stop/Start the associated service. And it should work for all scripting languages (Python, Perl, node.js), plus batch scripts such as GitBash, PowerShell, even old DOS bat scripts. pyGlue is the glue that sits between Windows Services and your script.

'''
A script to create a Windows Service, which, when started, will run an executable with the specified parameters.
Optionally, you can also specify a startup directory

To use this script you MUST define (in class Service)
1. A name for your service (short - preferably no spaces)
2. A display name for your service (the name visibile in Windows Services)
3. A description for your service (long details visible when you inspect the service in Windows Services)
4. The full path of the executable (usually C:/Python38/python.exe or C:WINDOWS/System32/WindowsPowerShell/v1.0/powershell.exe
5. The script which Python or PowerShell will run(or specify None if your executable is standalone - in which case you don't need pyGlue)
6. The startup directory (or specify None)
7. Any parameters for your script (or for your executable if you have no script)

NOTE: This does not make a portable script.
The associated '_svc_name.exe' in the dist folder will only work if the executable,
(and any optional startup directory) actually exist in those locations on the target system

Usage: 'pyGlue.exe [options] install|update|remove|start [...]|stop|restart [...]|debug [...]'
Options for 'install' and 'update' commands only:
        --username domain\\username : The Username the service is to run under
        --password password : The password for the username
        --startup [manual|auto|disabled|delayed] : How the service starts, default = manual
        --interactive : Allow the service to interact with the desktop.
        --perfmonini file: .ini file to use for registering performance monitor data
        --perfmondll file: .dll file to use when querying the service for performance data, default = perfmondata.dll
Options for 'start' and 'stop' commands only:
        --wait seconds: Wait for the service to actually start or stop.
                If you specify --wait with the 'stop' option, the service and all dependent services will be stopped,
                each waiting the specified period.
'''

# Import all the modules that make life easy
import servicemanager
import socket
import sys
import win32event
import win32service
import win32serviceutil
import win32evtlogutil
import os
from logging import Formatter, Handler
import logging
import subprocess


# Define the win32api class
class Service (win32serviceutil.ServiceFramework):
        # The following variable are edited by the build.sh script
        _svc_name_ = "TestService"
        _svc_display_name_ = "Test Service"
        _svc_description_ = "Test Running Python Scripts as a Service"
        service_exe = 'c:/Python27/python.exe'
        service_script = None
        service_params = []
        service_startDir = None

        # Initialize the service
        def __init__(self, args):
                win32serviceutil.ServiceFramework.__init__(self, args)
                self.hWaitStop = win32event.CreateEvent(None, 0, 0, None)
                self.configure_logging()
                socket.setdefaulttimeout(60)

        # Configure logging to the WINDOWS Event logs
        def configure_logging(self):
                self.formatter = Formatter('%(message)s')
                self.handler = logHandler()
                self.handler.setFormatter(self.formatter)
                self.logger = logging.getLogger()
                self.logger.addHandler(self.handler)
                self.logger.setLevel(logging.INFO)

        # Stop the service
        def SvcStop(self):
                self.ReportServiceStatus(win32service.SERVICE_STOP_PENDING)
                win32event.SetEvent(self.hWaitStop)

        # Run the service
        def SvcDoRun(self):
                self.main()

        # This is the service
        def main(self):

                # Log that we are starting
                servicemanager.LogMsg(servicemanager.EVENTLOG_INFORMATION_TYPE, servicemanager.PYS_SERVICE_STARTED,
                                                          (self._svc_name_, ''))

                # Fire off the real process that does the real work
                logging.info('%s - about to call Popen() to run %s %s %s', self._svc_name_, self.service_exe, self.service_script, self.service_params)
                self.process = subprocess.Popen([self.service_exe, self.service_script] + self.service_params, shell=False, cwd=self.service_startDir)
                logging.info('%s - started process %d', self._svc_name_, self.process.pid)

                # Wait until WINDOWS kills us - retrigger the wait for stop every 60 seconds
                rc = None
                while rc != win32event.WAIT_OBJECT_0:
                        rc = win32event.WaitForSingleObject(self.hWaitStop, (1 * 60 * 1000))

                # Shut down the real process and exit
                logging.info('%s - is terminating process %d', self._svc_name_, self.process.pid)
                self.process.terminate()
                logging.info('%s - is exiting', self._svc_name_)


class logHandler(Handler):
        '''
Emit a log record to the WINDOWS Event log
        '''

        def emit(self, record):
                servicemanager.LogInfoMsg(record.getMessage())


# The main code
if __name__ == '__main__':
        '''
Create a Windows Service, which, when started, will run an executable with the specified parameters.
        '''

        # Check that configuration contains valid values just in case this service has accidentally
        # been moved to a server where things are in different places
        if not os.path.isfile(Service.service_exe):
                print('Executable file({!s}) does not exist'.format(Service.service_exe), file=sys.stderr)
                sys.exit(0)
        if not os.access(Service.service_exe, os.X_OK):
                print('Executable file({!s}) is not executable'.format(Service.service_exe), file=sys.stderr)
                sys.exit(0)
        # Check that any optional startup directory exists
        if (Service.service_startDir is not None) and (not os.path.isdir(Service.service_startDir)):
                print('Start up directory({!s}) does not exist'.format(Service.service_startDir), file=sys.stderr)
                sys.exit(0)

        if len(sys.argv) == 1:
                servicemanager.Initialize()
                servicemanager.PrepareToHostSingle(Service)
                servicemanager.StartServiceCtrlDispatcher()
        else:
                # install/update/remove/start/stop/restart or debug the service
                # One of those command line options must be specified
                win32serviceutil.HandleCommandLine(Service)

Now there's a bit of editing and you don't want all your services called 'pyGlue'. So there's a script (build.sh) to plug in the bits and create a customized 'pyGlue' and create an '.exe'. It is this '.exe' which gets installed as a Windows Service. Once installed you can set it to run automatically.

#!/bin/sh
# This script build a Windows Service that will install/start/stop/remove a service that runs a script
# That is, executes Python to run a Python script, or PowerShell to run a PowerShell script, etc

if [ $# -lt 6 ]; then
        echo "Usage: build.sh Name Display Description Executable Script StartupDir [Params]..."
        exit 0
fi

name=$1
display=$2
desc=$3
exe=$4
script=$5
startDir=$6
shift; shift; shift; shift; shift; shift
params=
while [ $# -gt 0 ]; do
        if [ "${params}" != "" ]; then
                params="${params}, "
        fi
        params="${params}'$1'"
        shift
done

cat pyGlue.py | sed -e "s/pyGlue/${name}/g" | \
        sed -e "/_svc_name_ =/s?=.*?= '${name}'?" | \
        sed -e "/_svc_display_name_ =/s?=.*?= '${display}'?" | \
        sed -e "/_svc_description_ =/s?=.*?= '${desc}'?" | \
        sed -e "/service_exe =/s?=.*?= '$exe'?" | \
        sed -e "/service_script =/s?=.*?= '$script'?" | \
        sed -e "/service_params =/s?=.*?= [${params}]?" | \
        sed -e "/service_startDir =/s?=.*?= '${startDir}'?" > ${name}.py

cxfreeze ${name}.py --include-modules=win32timezone

Installation - copy the '.exe' the server and the script to the specified folder. Run the '.exe', as Administrator, with the 'install' option. Open Windows Services, as Adminstrator, and start you service. For upgrade, just copy the new version of the script and Stop/Start the service.

Now every server is different - different installations of Python, different folder structures. I maintain a folder for every server, with a copy of pyGlue.py and build.sh. And I create a 'serverBuild.sh' script for rebuilding all the service on that server.

# A script to build all the script based Services on this PC
sh build.sh AutoCode 'AutoCode Medical Documents' 'Autocode Medical Documents to SNOMED_CT and AIHW codes' C:/Python38/python.exe autocode.py C:/Users/russell/Documents/autocoding -S -T

Mongoose: Find, modify, save

I wanted to add something very important. I use JohnnyHK method a lot but I noticed sometimes the changes didn't persist to the database. When I used .markModified it worked.

User.findOne({username: oldUsername}, function (err, user) {
   user.username = newUser.username;
   user.password = newUser.password;
   user.rights = newUser.rights;

   user.markModified(username)
   user.markModified(password)
   user.markModified(rights)
    user.save(function (err) {
    if(err) {
        console.error('ERROR!');
    }
});
});

tell mongoose about the change with doc.markModified('pathToYourDate') before saving.

Launch iOS simulator from Xcode and getting a black screen, followed by Xcode hanging and unable to stop tasks

If you should loose your entry point in your Storyboard or simply wish to change the entry point you can specify this in Interface Builder. To set a new entry point you must first decide which ViewController will act as the new entry point and in the Attribute Inspector select the Initial Scene checkbox.

You can try: http://www.scott-sherwood.com/ios-5-specifying-the-entry-point-of-your-storyboard/

Selecting multiple columns in a Pandas dataframe

df[['a', 'b']]  # Select all rows of 'a' and 'b'column 
df.loc[0:10, ['a', 'b']]  # Index 0 to 10 select column 'a' and 'b'
df.loc[0:10, 'a':'b']  # Index 0 to 10 select column 'a' to 'b'
df.iloc[0:10, 3:5]  # Index 0 to 10 and column 3 to 5
df.iloc[3, 3:5]  # Index 3 of column 3 to 5

iterating and filtering two lists using java 8

// produce the filter set by streaming the items from list 2
// assume list2 has elements of type MyClass where getStr gets the
// string that might appear in list1
Set<String> unavailableItems = list2.stream()
    .map(MyClass::getStr)
    .collect(Collectors.toSet());

// stream the list and use the set to filter it
List<String> unavailable = list1.stream()
            .filter(e -> unavailableItems.contains(e))
            .collect(Collectors.toList());

No provider for Http StaticInjectorError

I was trying to fix the issue for about an hour and just deiced to restart the server. Only to see the issue is fixed.

If you make changes to APP module and the issue remains the same, stop the server and try running the serve command again.

Using ionic 4 with angular 7

python getoutput() equivalent in subprocess

To catch errors with subprocess.check_output(), you can use CalledProcessError. If you want to use the output as string, decode it from the bytecode.

# \return String of the output, stripped from whitespace at right side; or None on failure.
def runls():
    import subprocess
    try:
        byteOutput = subprocess.check_output(['ls', '-a'], timeout=2)
        return byteOutput.decode('UTF-8').rstrip()
    except subprocess.CalledProcessError as e:
        print("Error in ls -a:\n", e.output)
        return None

Understanding lambda in python and using it to pass multiple arguments

Why do you need to state both 'x' and 'y' before the ':'?

You could actually in some situations(when you have only one argument) do not put the x and y before ":".

>>> flist = []
>>> for i in range(3):
...     flist.append(lambda : i)

but the i in the lambda will be bound by name, so,

>>> flist[0]()
2
>>> flist[2]()
2
>>>

different from what you may want.

Spring MVC 4: "application/json" Content Type is not being set correctly

First thing to understand is that the RequestMapping#produces() element in

@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")

serves only to restrict the mapping for your request handlers. It does nothing else.

Then, given that your method has a return type of String and is annotated with @ResponseBody, the return value will be handled by StringHttpMessageConverter which sets the Content-type header to text/plain. If you want to return a JSON string yourself and set the header to application/json, use a return type of ResponseEntity (get rid of @ResponseBody) and add appropriate headers to it.

@RequestMapping(value = "/json", method = RequestMethod.GET, produces = "application/json")
public ResponseEntity<String> bar() {
    final HttpHeaders httpHeaders= new HttpHeaders();
    httpHeaders.setContentType(MediaType.APPLICATION_JSON);
    return new ResponseEntity<String>("{\"test\": \"jsonResponseExample\"}", httpHeaders, HttpStatus.OK);
}

Note that you should probably have

<mvc:annotation-driven /> 

in your servlet context configuration to set up your MVC configuration with the most suitable defaults.

Difference between $(document.body) and $('body')

I have found a pretty big difference in timing when testing in my browser.

I used the following script:

WARNING: running this will freeze your browser a bit, might even crash it.

_x000D_
_x000D_
var n = 10000000, i;_x000D_
i = n;_x000D_
console.time('selector');_x000D_
while (i --> 0){_x000D_
    $("body");_x000D_
}_x000D_
_x000D_
console.timeEnd('selector');_x000D_
_x000D_
i = n;_x000D_
console.time('element');_x000D_
while (i --> 0){_x000D_
    $(document.body);_x000D_
}_x000D_
_x000D_
console.timeEnd('element');
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

I did 10 million interactions, and those were the results (Chrome 65):

selector: 19591.97509765625ms
element: 4947.8759765625ms

Passing the element directly is around 4 times faster than passing the selector.

How to create a scrollable Div Tag Vertically?

Well, your code worked for me (running Chrome 5.0.307.9 and Firefox 3.5.8 on Ubuntu 9.10), though I switched

overflow-y: scroll;

to

overflow-y: auto;

Demo page over at: http://davidrhysthomas.co.uk/so/tableDiv.html.

xhtml below:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

<head>
    <META http-equiv="Content-Type" content="text/html; charset=UTF-8">

    <title>Div in table</title>
    <link rel="stylesheet" type="text/css" href="css/stylesheet.css" />

        <style type="text/css" media="all">

        th      {border-bottom: 2px solid #ccc; }

        th,td       {padding: 0.5em 1em; 
                margin: 0;
                border-collapse: collapse;
                }

        tr td:first-child
                {border-right: 2px solid #ccc; } 

        td > div    {width: 249px;
                height: 299px;
                background-color:Gray;
                overflow-y: auto;
                max-width:230px;
                max-height:100px;
                }
        </style>

    <script type="text/javascript" src="js/jquery.js"></script>

    <script type="text/javascript">

    </script>

</head>

<body>

<div>

    <table>

        <thead>
            <tr><th>This is column one</th><th>This is column two</th><th>This is column three</th>
        </thead>



        <tbody>
            <tr><td>This is row one</td><td>data point 2.1</td><td>data point 3.1</td>
            <tr><td>This is row two</td><td>data point 2.2</td><td>data point 3.2</td>
            <tr><td>This is row three</td><td>data point 2.3</td><td>data point 3.3</td>
            <tr><td>This is row four</td><td><div><p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum ultricies mattis dolor. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Vestibulum a accumsan purus. Vivamus semper tempus nisi et convallis. Aliquam pretium rutrum lacus sed auctor. Phasellus viverra elit vel neque lacinia ut dictum mauris aliquet. Etiam elementum iaculis lectus, laoreet tempor ligula aliquet non. Mauris ornare adipiscing feugiat. Vivamus condimentum luctus tortor venenatis fermentum. Maecenas eu risus nec leo vehicula mattis. In nisi nibh, fermentum vitae tincidunt non, mattis eu metus. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Nunc vel est purus. Ut accumsan, elit non lacinia porta, nibh magna pretium ligula, sed iaculis metus tortor aliquam urna. Duis commodo tincidunt aliquam. Maecenas in augue ut ligula sodales elementum quis vitae risus. Vivamus mollis blandit magna, eu fringilla velit auctor sed.</p></div></td><td>data point 3.4</td>
            <tr><td>This is row five</td><td>data point 2.5</td><td>data point 3.5</td>
            <tr><td>This is row six</td><td>data point 2.6</td><td>data point 3.6</td>
            <tr><td>This is row seven</td><td>data point 2.7</td><td>data point 3.7</td>
        </body>



    </table>

</div>

</body>

</html>

Android appcompat v7:23

Ran into a similar issue using React Native

> Could not find com.android.support:appcompat-v7:23.0.1.

the Support Libraries are Local Maven repository for Support Libraries

enter image description here

How I add Headers to http.get or http.post in Typescript and angular 2?

Be sure to declare HttpHeaders without null values.

    this.http.get('url', {headers: new HttpHeaders({'a': a || '', 'b': b || ''}))

Otherwise, if you try to add a null value to HttpHeaders it will give you an error.

ASP.NET Setting width of DataBound column in GridView

Width can be set to specific column as below: By percentages:

<asp:BoundField HeaderText="UserInfo"  DataField="UserInfo"  
SortExpression="UserInfo" ItemStyle-Width="100%"></asp:BoundField>

OR

By pixel:

<asp:BoundField HeaderText="UserInfo"  DataField="UserInfo"  
SortExpression="UserInfo" ItemStyle-Width="500px"></asp:BoundField>

How do I read image data from a URL in Python?

select the image in chrome, right click on it, click on Copy image address, paste it into a str variable (my_url) to read the image:

import shutil
import requests

my_url = 'https://www.washingtonian.com/wp-content/uploads/2017/06/6-30-17-goat-yoga-congressional-cemetery-1-994x559.jpg'
response = requests.get(my_url, stream=True)
with open('my_image.png', 'wb') as file:
    shutil.copyfileobj(response.raw, file)
del response

open it;

from PIL import Image

img = Image.open('my_image.png')
img.show()

What is the default access modifier in Java?

It depends on the context.

When it's within a class:

class example1 {

    int a = 10; // This is package-private (visible within package)

    void method1() // This is package-private as well.
    {
        -----
    }
}

When it's within a interface:

interface example2 {

    int b = 10; // This is public and static.
    void method2(); // This is public and abstract
}

How to remove ASP.Net MVC Default HTTP Headers?

As shown on Removing standard server headers on Windows Azure Web Sites page, you can remove headers with the following:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <system.webServer>
    <httpProtocol>
      <customHeaders>
        <clear />
      </customHeaders>
    </httpProtocol>
    <security>
      <requestFiltering removeServerHeader="true"/>
    </security>
  </system.webServer>
  <system.web>
    <httpRuntime enableVersionHeader="false" />
  </system.web>
</configuration>

This removes the Server header, and the X- headers.

This worked locally in my tests in Visual Studio 2015.

Don't understand why UnboundLocalError occurs (closure)

try this

counter = 0

def increment():
  global counter
  counter += 1

increment()

Copy table from one database to another

Assuming that you want different names for the tables.

If you are using PHPmyadmin you can use their SQL option in the menu. Then you simply copy the SQL-code from the first table and paste it into the new table.

That worked out for me when I was moving from localhost to a webhost. Hope it works for you!

Serializing class instance to JSON

Use arbitrary, extensible object, and then serialize it to JSON:

import json

class Object(object):
    pass

response = Object()
response.debug = []
response.result = Object()

# Any manipulations with the object:
response.debug.append("Debug string here")
response.result.body = "404 Not Found"
response.result.code = 404

# Proper JSON output, with nice formatting:
print(json.dumps(response, indent=4, default=lambda x: x.__dict__))

HttpClient.GetAsync(...) never returns when using await/async

You are misusing the API.

Here's the situation: in ASP.NET, only one thread can handle a request at a time. You can do some parallel processing if necessary (borrowing additional threads from the thread pool), but only one thread would have the request context (the additional threads do not have the request context).

This is managed by the ASP.NET SynchronizationContext.

By default, when you await a Task, the method resumes on a captured SynchronizationContext (or a captured TaskScheduler, if there is no SynchronizationContext). Normally, this is just what you want: an asynchronous controller action will await something, and when it resumes, it resumes with the request context.

So, here's why test5 fails:

  • Test5Controller.Get executes AsyncAwait_GetSomeDataAsync (within the ASP.NET request context).
  • AsyncAwait_GetSomeDataAsync executes HttpClient.GetAsync (within the ASP.NET request context).
  • The HTTP request is sent out, and HttpClient.GetAsync returns an uncompleted Task.
  • AsyncAwait_GetSomeDataAsync awaits the Task; since it is not complete, AsyncAwait_GetSomeDataAsync returns an uncompleted Task.
  • Test5Controller.Get blocks the current thread until that Task completes.
  • The HTTP response comes in, and the Task returned by HttpClient.GetAsync is completed.
  • AsyncAwait_GetSomeDataAsync attempts to resume within the ASP.NET request context. However, there is already a thread in that context: the thread blocked in Test5Controller.Get.
  • Deadlock.

Here's why the other ones work:

  • (test1, test2, and test3): Continuations_GetSomeDataAsync schedules the continuation to the thread pool, outside the ASP.NET request context. This allows the Task returned by Continuations_GetSomeDataAsync to complete without having to re-enter the request context.
  • (test4 and test6): Since the Task is awaited, the ASP.NET request thread is not blocked. This allows AsyncAwait_GetSomeDataAsync to use the ASP.NET request context when it is ready to continue.

And here's the best practices:

  1. In your "library" async methods, use ConfigureAwait(false) whenever possible. In your case, this would change AsyncAwait_GetSomeDataAsync to be var result = await httpClient.GetAsync("http://stackoverflow.com", HttpCompletionOption.ResponseHeadersRead).ConfigureAwait(false);
  2. Don't block on Tasks; it's async all the way down. In other words, use await instead of GetResult (Task.Result and Task.Wait should also be replaced with await).

That way, you get both benefits: the continuation (the remainder of the AsyncAwait_GetSomeDataAsync method) is run on a basic thread pool thread that doesn't have to enter the ASP.NET request context; and the controller itself is async (which doesn't block a request thread).

More information:

Update 2012-07-13: Incorporated this answer into a blog post.

How to convert timestamps to dates in Bash?

I have written a script that does this myself:

#!/bin/bash
LANG=C
if [ -z "$1" ]; then
    if [  "$(tty)" = "not a tty" ]; then
            p=`cat`;
    else
            echo "No timestamp given."
            exit
    fi
else
    p=$1
fi
echo $p | gawk '{ print strftime("%c", $0); }'

Shall we always use [unowned self] inside closure in Swift

Here is brilliant quotes from Apple Developer Forums described delicious details:

unowned vs unowned(safe) vs unowned(unsafe)

unowned(safe) is a non-owning reference that asserts on access that the object is still alive. It's sort of like a weak optional reference that's implicitly unwrapped with x! every time it's accessed. unowned(unsafe) is like __unsafe_unretained in ARC—it's a non-owning reference, but there's no runtime check that the object is still alive on access, so dangling references will reach into garbage memory. unowned is always a synonym for unowned(safe) currently, but the intent is that it will be optimized to unowned(unsafe) in -Ofast builds when runtime checks are disabled.

unowned vs weak

unowned actually uses a much simpler implementation than weak. Native Swift objects carry two reference counts, and unowned references bump the unowned reference count instead of the strong reference count. The object is deinitialized when its strong reference count reaches zero, but it isn't actually deallocated until the unowned reference count also hits zero. This causes the memory to be held onto slightly longer when there are unowned references, but that isn't usually a problem when unowned is used because the related objects should have near-equal lifetimes anyway, and it's much simpler and lower-overhead than the side-table based implementation used for zeroing weak references.

Update: In modern Swift weak internally uses the same mechanism as unowned does. So this comparison is incorrect because it compares Objective-C weak with Swift unonwed.

Reasons

What is the purpose of keeping the memory alive after owning references reach 0? What happens if code attempts to do something with the object using an unowned reference after it is deinitialized?

The memory is kept alive so that its retain counts are still available. This way, when someone attempts to retain a strong reference to the unowned object, the runtime can check that the strong reference count is greater than zero in order to ensure that it is safe to retain the object.

What happens to owning or unowned references held by the object? Is their lifetime decoupled from the object when it is deinitialized or is their memory also retained until the object is deallocated after the last unowned reference is released?

All resources owned by the object are released as soon as the object's last strong reference is released, and its deinit is run. Unowned references only keep the memory alive—aside from the header with the reference counts, its contents is junk.

Excited, huh?

Viewing all defined variables

As RedBlueThing and analog said:

  • dir() gives a list of in scope variables
  • globals() gives a dictionary of global variables
  • locals() gives a dictionary of local variables

Using the interactive shell (version 2.6.9), after creating variables a = 1 and b = 2, running dir() gives

['__builtins__', '__doc__', '__name__', '__package__', 'a', 'b']

running locals() gives

{'a': 1, 'b': 2, '__builtins__': <module '__builtin__' (built-in)>, '__package__': None, '__name__': '__main__', '__doc__': None}

Running globals() gives exactly the same answer as locals() in this case.

I haven't gotten into any modules, so all the variables are available as both local and global variables. locals() and globals() list the values of the variables as well as the names; dir() only lists the names.

If I import a module and run locals() or globals() inside the module, dir() still gives only a small number of variables; it adds __file__ to the variables listed above. locals() and globals() also list the same variables, but in the process of printing out the dictionary value for __builtin__, it lists a far larger number of variables: built-in functions, exceptions, and types such as "'type': <type 'type'>", rather than just the brief <module '__builtin__' (built-in)> as shown above.

For more about dir() see Python 2.7 quick reference at New Mexico Tech or the dir() function at ibiblio.org.

For more about locals() and globals() see locals and globals at Dive Into Python and a page about globals at New Mexico Tech.

[Comment: @Kurt: You gave a link to enumerate-or-list-all-variables-in-a-program-of-your-favorite-language-here but that answer has a mistake in it. The problem there is: type(name) in that example will always return <type 'str'>. You do get a list of the variables, which answers the question, but with incorrect types listed beside them. This was not obvious in your example because all the variables happened to be strings anyway; however, what it's returning is the type of the name of the variable instead of the type of the variable. To fix this: instead of print type(name) use print eval('type(' + name + ')'). I apologize for posting a comment in the answer section but I don't have comment posting privileges, and the other question is closed.]

Making a flex item float right

You can't use float inside flex container and the reason is that float property does not apply to flex-level boxes as you can see here Fiddle.

So if you want to position child element to right of parent element you can use margin-left: auto but now child element will also push other div to the right as you can see here Fiddle.

What you can do now is change order of elements and set order: 2 on child element so it doesn't affect second div

_x000D_
_x000D_
.parent {_x000D_
  display: flex;_x000D_
}_x000D_
.child {_x000D_
  margin-left: auto;_x000D_
  order: 2;_x000D_
}
_x000D_
<div class="parent">_x000D_
  <div class="child">Ignore parent?</div>_x000D_
  <div>another child</div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Solution to "subquery returns more than 1 row" error

You can use in():

select * 
from table
where id in (multiple row query)

or use a join:

select distinct t.* 
from source_of_id_table s
join table t on t.id = s.t_id
where <conditions for source_of_id_table>

The join is never a worse choice for performance, and depending on the exact situation and the database you're using, can give much better performance.

Making an iframe responsive

Simple, with CSS:

iframe{
width: 100%;
max-width: 800px /*this can be anything you wish, to show, as default size*/
}

Please, note: But it won't make the content inside it responsive!

2nd EDIT:: There are two types of responsive iframes, depending on their inner content:

one that is when the inside of the iframe only contains a video or an image or many vertically positioned, for which the above two-rows of CSS code is almost completely enough, and the aspect ratio has meaning...

and the other is the:

contact/registration form type of content, where not the aspect ratio do we have to keep, but to prevent the scrollbar from appearing, and the content under-flowing the container. On mobile you don't see the scrollbar, you just scroll until you see the content (of the iframe). Of course you give it at least some kind of height, to make the content height adapt to the vertical space occurring on a narrower screen - with media queries, like, for example:

@media (max-width: 640px){
iframe{
height: 1200px /*whatever you need, to make the scrollbar hide on testing, and the content of the iframe reveal (on mobile/phone or other target devices) */
}
}
@media (max-width: 420px){
iframe{
height: 1600px /*and so on until and as needed */
}
}

How to check if IsNumeric

There's a slightly better way:

int valueParsed;
if(Int32.TryParse(txtMyText.Text.Trim(), out valueParsed))
{ ... }

If you try to parse the text and it can't be parsed, the Int32.Parse method will raise an exception. I think it is better for you to use the TryParse method which will capture the exception and let you know as a boolean if any exception was encountered.

There are lot of complications in parsing text which Int32.Parse takes into account. It is foolish to duplicate the effort. As such, this is very likely the approach taken by VB's IsNumeric. You can also customize the parsing rules through the NumberStyles enumeration to allow hex, decimal, currency, and a few other styles.

Another common approach for non-web based applications is to restrict the input of the text box to only accept characters which would be parseable into an integer.

EDIT: You can accept a larger variety of input formats, such as money values ("$100") and exponents ("1E4"), by specifying the specific NumberStyles:

int valueParsed;
if(Int32.TryParse(txtMyText.Text.Trim(), NumberStyles.AllowCurrencySymbol | NumberStyles.AllowExponent, CultureInfo.CurrentCulture, out valueParsed))
{ ... }

... or by allowing any kind of supported formatting:

int valueParsed;
if(Int32.TryParse(txtMyText.Text.Trim(), NumberStyles.Any, CultureInfo.CurrentCulture, out valueParsed))
{ ... }

Uninstall Node.JS using Linux command line?

If you installed from source, you can issue the following command:

sudo make uninstall

If you followed the instructions on https://github.com/nodejs/node/wiki to install to your $HOME/local/node, then you have to type the following before the line above:

./configure --prefix=$HOME/local/node

Vue template or render function not defined yet I am using neither?

Something like this should resolve the issue..

Vue.component(
'example-component', 
require('./components/ExampleComponent.vue').default);

How do I use vim registers?

A cool trick is to use "1p to paste the last delete/change (, and then use . to repeatedly to paste the subsequent deletes. In other words, "1p... is basically equivalent to "1p"2p"3p"4p.

You can use this to reverse-order a handful of lines: dddddddddd"1p....

Execute action when back bar button of UINavigationController is pressed

Here is the simplest possible Swift 5 solution that doesn't require you to create a custom back button and give up all that UINavigationController left button functionality you get for free.

As Brandon A recommends above, you need need to implement UINavigationControllerDelegate in the view controller you want to interact with before returning to it. A good way is to create an unwind segue that you can perform manually or automatically and reuse the same code from a custom done button or the back button.

First, make your view controller of interest (the one you want to detect returning to) a delegate of the navigation controller in its viewDidLoad:

override func viewDidLoad() {
    super.viewDidLoad()
    navigationController?.delegate = self
}

Second, add an extension at the bottom of the file that overrides navigationController(willShow:animated:)

extension PickerTableViewController: UINavigationControllerDelegate {

    func navigationController(_ navigationController: UINavigationController,
                              willShow viewController: UIViewController,
                              animated: Bool) {

        if let _ = viewController as? EditComicBookViewController {

            let selectedItemRow = itemList.firstIndex(of: selectedItemName)
            selectedItemIndex = IndexPath(row: selectedItemRow!, section: 0)

            if let selectedCell = tableView.cellForRow(at: selectedItemIndex) {
                performSegue(withIdentifier: "PickedItem", sender: selectedCell)
            }
        }
    }
}

Since your question included a UITableViewController, I included a way to get the index path of the row the user tapped.

Declaration of Methods should be Compatible with Parent Methods in PHP

This message means that there are certain possible method calls which may fail at run-time. Suppose you have

class A { public function foo($a = 1) {;}}
class B extends A { public function foo($a) {;}}
function bar(A $a) {$a->foo();}

The compiler only checks the call $a->foo() against the requirements of A::foo() which requires no parameters. $a may however be an object of class B which requires a parameter and so the call would fail at runtime.

This however can never fail and does not trigger the error

class A { public function foo($a) {;}}
class B extends A { public function foo($a = 1) {;}}
function bar(A $a) {$a->foo();}

So no method may have more required parameters than its parent method.

The same message is also generated when type hints do not match, but in this case PHP is even more restrictive. This gives an error:

class A { public function foo(StdClass $a) {;}}
class B extends A { public function foo($a) {;}}

as does this:

class A { public function foo($a) {;}}
class B extends A { public function foo(StdClass $a) {;}}

That seems more restrictive than it needs to be and I assume is due to internals.

Visibility differences cause a different error, but for the same basic reason. No method can be less visible than its parent method.

How to Remove the last char of String in C#?

If you are using string datatype, below code works:

string str = str.Remove(str.Length - 1);

But when you have StringBuilder, you have to specify second parameter length as well.

SB

That is,

string newStr = sb.Remove(sb.Length - 1, 1).ToString();

To avoid below error:

SB2

Setting Action Bar title and subtitle

This is trivial one-liner in Kotlin

supportActionBar?.title = getString(R.string.coolTitle)

Getting raw SQL query string from PDO prepared statements

The $queryString property mentioned will probably only return the query passed in, without the parameters replaced with their values. In .Net, I have the catch part of my query executer do a simple search replace on the parameters with their values which was supplied so that the error log can show actual values that were being used for the query. You should be able to enumerate the parameters in PHP, and replace the parameters with their assigned value.

Set language for syntax highlighting in Visual Studio Code

To permanently set the language syntax:
open settings.json file

*) format all txt files with javascript formatting

"files.associations": {
        "*.txt": "javascript"

 }

*) format all unsaved files (untitled-1 etc) to javascript:

"files.associations": {
        "untitled-*": "javascript"

 }

How to insert 1000 rows at a time

You can use the following CTE as well. You can just modify it as you find fit. But this will add the same values into the student CTE.

This will add 1000 records but you can change it to 10000 or to a maximum of 32767

;WITH thetable(rowid,sname,semail,spassword) AS
(
    SELECT 1  , 'name' , 'email' , 'password'
    UNION ALL
    SELECT rowid+1 ,'name' , 'email' , 'password' 
    FROM thetable WHERE rowid < 1000
)

SELECT rowid,sname,semail,spassword 
FROM thetable ORDER BY rowid
OPTION (MAXRECURSION 1000);

AngularJS : Custom filters and ng-repeat

If you still want a custom filter you can pass in the search model to the filter:

<article data-ng-repeat="result in results | cartypefilter:search" class="result">

Where definition for the cartypefilter can look like this:

app.filter('cartypefilter', function() {
  return function(items, search) {
    if (!search) {
      return items;
    }

    var carType = search.carType;
    if (!carType || '' === carType) {
      return items;
    }

    return items.filter(function(element, index, array) {
      return element.carType.name === search.carType;
    });

  };
});

http://plnkr.co/edit/kBcUIayO8tQsTTjTA2vO?p=preview

Setting active profile and config location from command line in spring boot

There's another way by setting the OS variable, SPRING_PROFILES_ACTIVE.

for eg :

SPRING_PROFILES_ACTIVE=dev gradle clean bootRun

Reference : How to set active Spring profiles

Cycles in family tree software

You should focus on what really makes value for your software. Is the time spent on making it work for ONE consumer worth the price of the license ? Likely not.

I advise you to apologize to this customer, tell him that his situation is out of scope for your software and issue him a refund.

Where is the <conio.h> header file on Linux? Why can't I find <conio.h>?

conio.h is a C header file used in old MS-DOS compilers to create text user interfaces. Compilers that targeted non-DOS operating systems, such as Linux, Win32 and OS/2, provided different implementations of these functions.

The #include <curses.h> will give you almost all the functionalities that was provided in conio.h

nucurses need to be installed at the first place

In deb based Distros use

sudo apt-get install libncurses5-dev libncursesw5-dev

And in rpm based distros use

sudo yum install ncurses-devel ncurses

For getch() class of functions, you can try this

Best practices for copying files with Maven

To summarize some of the fine answers above: Maven is designed to build modules and copy the results to a Maven repository. Any copying of modules to a deployment/installer-input directory must be done outside the context of Maven's core functionality, e.g. with the Ant/Maven copy command.

How to rearrange Pandas column sequence?

Feel free to disregard this solution as subtracting a list from an Index does not preserve the order of the original Index, if that's important.

In [61]: df.reindex(columns=pd.Index(['x', 'y']).append(df.columns - ['x', 'y']))
Out[61]: 
    x  y  a  b
0   3 -1  1  2
1   6 -2  2  4
2   9 -3  3  6
3  12 -4  4  8

Deleting all pending tasks in celery / rabbitmq

1. To properly purge the queue of waiting tasks you have to stop all the workers (http://celery.readthedocs.io/en/latest/faq.html#i-ve-purged-messages-but-there-are-still-messages-left-in-the-queue):

$ sudo rabbitmqctl stop

or (in case RabbitMQ/message broker is managed by Supervisor):

$ sudo supervisorctl stop all

2. ...and then purge the tasks from a specific queue:

$ cd <source_dir>
$ celery amqp queue.purge <queue name>

3. Start RabbitMQ:

$ sudo rabbitmqctl start

or (in case RabbitMQ is managed by Supervisor):

$ sudo supervisorctl start all

Continuous Integration vs. Continuous Delivery vs. Continuous Deployment

Neither the question nor the answers really fit my simple way of thinking about it. I'm a consultant and have synchronized these definitions with a number of Dev teams and DevOps people, but am curious about how it matches with the industry at large:

Basically I think of the agile practice of continuous delivery like a continuum:

Not continuous (everything manual) 0% ----> 100% Continuous Delivery of Value (everything automated)

Steps towards continuous delivery:

Zero. Nothing is automated when devs check in code... You're lucky if they have compiled, run, or performed any testing prior to check-in.

  1. Continuous Build: automated build on every check-in, which is the first step, but does nothing to prove functional integration of new code.

  2. Continuous Integration (CI): automated build and execution of at least unit tests to prove integration of new code with existing code, but preferably integration tests (end-to-end).

  3. Continuous Deployment (CD): automated deployment when code passes CI at least into a test environment, preferably into higher environments when quality is proven either via CI or by marking a lower environment as PASSED after manual testing. I.E., testing may be manual in some cases, but promoting to next environment is automatic.

  4. Continuous Delivery: automated publication and release of the system into production. This is CD into production plus any other configuration changes like setup for A/B testing, notification to users of new features, notifying support of new version and change notes, etc.

EDIT: I would like to point out that there's a difference between the concept of "continuous delivery" as referenced in the first principle of the Agile Manifesto (http://agilemanifesto.org/principles.html) and the practice of Continuous Delivery, as seems to be referenced by the context of the question. The principle of continuous delivery is that of striving to reduce the Inventory waste as described in Lean thinking (http://www.miconleansixsigma.com/8-wastes.html). The practice of Continuous Delivery (CD) by agile teams has emerged in the many years since the Agile Manifesto was written in 2001. This agile practice directly addresses the principle, although they are different things and apparently easily confused.

Git asks for username every time I push

Permanently authenticating with Git repositories

Run following command to enable credential caching:

$ git config credential.helper store
$ git push https://github.com/repo.git

Username for 'https://github.com': <USERNAME>
Password for 'https://[email protected]': <PASSWORD>

Use should also specify caching expire

git config --global credential.helper "cache --timeout 7200"

After enabling credential caching, it will be cached for 7200 seconds (2 hour).


Read credentials Docs

$ git help credentials

How to bind multiple values to a single WPF TextBlock?

If these are just going to be textblocks (and thus one way binding), and you just want to concatenate values, just bind two textblocks and put them in a horizontal stackpanel.

    <StackPanel Orientation="Horizontal">
        <TextBlock Text="{Binding Name}"/>
        <TextBlock Text="{Binding ID}"/>
    </StackPanel>

That will display the text (which is all Textblocks do) without having to do any more coding. You might put a small margin on them to make them look right though.

Check if an element is present in an array

Since ECMAScript6, one can use Set :

var myArray = ['A', 'B', 'C'];
var mySet = new Set(myArray);
var hasB = mySet.has('B'); // true
var hasZ = mySet.has('Z'); // false

Image steganography that could survive jpeg compression

Quite a few applications seem to implement Steganography on JPEG, so it's feasible:

http://www.jjtc.com/Steganography/toolmatrix.htm

Here's an article regarding a relevant algorithm (PM1) to get you started:

http://link.springer.com/article/10.1007%2Fs00500-008-0327-7#page-1

preventDefault() on an <a> tag

This is a non-JQuery solution I just tested and it works.

<html lang="en">
<head>
<script type="text/javascript">
addEventListener("load",function(){
    var links= document.getElementsByTagName("a");
    for (var i=0;i<links.length;i++){
        links[i].addEventListener("click",function(e){
        alert("NOPE!, I won't take you there haha");
        //prevent event action
        e.preventDefault();
        })
    }
}); 

</script>
</head>
<body>
<div>
<ul>
    <li><a href="http://www.google.com">Google</a></li>
    <li><a href="http://www.facebook.com">Facebook</a></li>
    <p id="p1">Paragraph</p>
</ul>
</div>
<p>By Jefrey Bulla</p>
</body>
</html>

How to JSON decode array elements in JavaScript?

If you get this text in an alert:

function(){return JSON.encode(this);}

when you try alert(myArray[i]), then there are a few possibilities:

  • myArray[i] is a function (most likely)
  • myArray[i] is the literal string "function(){return JSON.encode(this);}"
  • myArray[i] has a .toString() method that returns that function or that string. This is the least likely of the three.

The simplest way to tell would be to check typeof(myArray[i]).

ORA-06508: PL/SQL: could not find program unit being called

seems like opening a new session is the key.

see this answer.

and here is an awesome explanation about this error

Center an element in Bootstrap 4 Navbar

Try this.

.nav-tabs > li{
    float:none !important;
    display:inline-block !important;
}

.nav-tabs {
    text-align:center !important;
}

Auto-Submit Form using JavaScript

You need to specify a frame, a target otherwise your script will vanish on first submit!

Change document.myForm with document.forms["myForm"]:

<form name="myForm" id="myForm" target="_myFrame" action="test.php" method="POST">
    <p>
        <input name="test" value="test" />
    </p>
    <p>
        <input type="submit" value="Submit" />
    </p>
</form>

<script type="text/javascript">
    window.onload=function(){
        var auto = setTimeout(function(){ autoRefresh(); }, 100);

        function submitform(){
          alert('test');
          document.forms["myForm"].submit();
        }

        function autoRefresh(){
           clearTimeout(auto);
           auto = setTimeout(function(){ submitform(); autoRefresh(); }, 10000);
        }
    }
</script>

How to handle AssertionError in Python and find out which line or statement it occurred on?

Use the traceback module:

import sys
import traceback

try:
    assert True
    assert 7 == 7
    assert 1 == 2
    # many more statements like this
except AssertionError:
    _, _, tb = sys.exc_info()
    traceback.print_tb(tb) # Fixed format
    tb_info = traceback.extract_tb(tb)
    filename, line, func, text = tb_info[-1]

    print('An error occurred on line {} in statement {}'.format(line, text))
    exit(1)

JVM option -Xss - What does it do exactly?

It indeed sets the stack size on a JVM.

You should touch it in either of these two situations:

  • StackOverflowError (the stack size is greater than the limit), increase the value
  • OutOfMemoryError: unable to create new native thread (too many threads, each thread has a large stack), decrease it.

The latter usually comes when your Xss is set too large - then you need to balance it (testing!)

Search of table names

I know this is an old thread, but if you prefer case-insensitive searching:

SELECT * FROM INFORMATION_SCHEMA.TABLES 
WHERE Lower(TABLE_NAME) LIKE Lower('%%')

How remove border around image in css?

Thank for the answers,

The border is removed for Internet Explorer, but this there for Firefox.

So, I added this class to the img:

.clearBorder{border:none;}

And it worked!

New xampp security concept: Access Forbidden Error 403 - Windows 7 - phpMyAdmin

You will have to edit 2 files - 1. httpd-vhosts.conf & 2. httpd-xampp.conf

NOTE : Make sure u backup files ( httpd-xampp.conf ) and ( httpd-vhosts.conf ) , Both Files are located in Drive:\xampp\apache\conf\extra

Open httpd-vhosts.conf file and in the bottom of the file change it

<VirtualHost *:80>
DocumentRoot “E:/xampp/htdocs/”
ServerName localhost
<Directory E:/xampp/htdocs/>.
Require all granted 
</Directory>
</VirtualHost>

Here E:/xampp is my project workspace, you can change it as per your settings

and Second Change is on httpd-xampp.conf file and in the bottom of the file change it

#
# New XAMPP security concept
#
<LocationMatch “^/(?i:(?:xampp|security|licenses|phpmyadmin|webalizer|server-status|server-info))”>
Order deny,allow
Allow from all
Allow from ::1 127.0.0.0/8
ErrorDocument 403 /error/XAMPP_FORBIDDEN.html.var
</LocationMatch>

How to write MySQL query where A contains ( "a" or "b" )

Two options:

  1. Use the LIKE keyword, along with percent signs in the string

    select * from table where field like '%a%' or field like '%b%'.
    

    (note: If your search string contains percent signs, you'll need to escape them)

  2. If you're looking for more a complex combination of strings than you've specified in your example, you could regular expressions (regex):

    See the MySQL manual for more on how to use them: http://dev.mysql.com/doc/refman/5.1/en/regexp.html

Of these, using LIKE is the most usual solution -- it's standard SQL, and in common use. Regex is less commonly used but much more powerful.

Note that whichever option you go with, you need to be aware of possible performance implications. Searching for sub-strings like this will mean that the query will have to scan the entire table. If you have a large table, this could make for a very slow query, and no amount of indexing is going to help.

If this is an issue for you, and you'r going to need to search for the same things over and over, you may prefer to do something like adding a flag field to the table which specifies that the string field contains the relevant sub-strings. If you keep this flag field up-to-date when you insert of update a record, you could simply query the flag when you want to search. This can be indexed, and would make your query much much quicker. Whether it's worth the effort to do that is up to you, it'll depend on how bad the performance is using LIKE.

How to: Add/Remove Class on mouseOver/mouseOut - JQuery .hover?

Your selector is missing a . and though you say you want to change the border-color - you're adding and removing a class that sets the background-color

Headers and client library minor version mismatch

Changing PHP version from 5.6 to 5.5 Fixed it.

You have to go to control panel > CGI Script and change PHP version there.

Javascript Regex: How to put a variable inside a regular expression?

You can create regular expressions in JS in one of two ways:

  1. Using regular expression literal - /ab{2}/g
  2. Using the regular expression constructor - new RegExp("ab{2}", "g") .

Regular expression literals are constant, and can not be used with variables. This could be achieved using the constructor. The stracture of the RegEx constructor is

new RegExp(regularExpressionString, modifiersString)

You can embed variables as part of the regularExpressionString. For example,

var pattern="cd"
var repeats=3
new RegExp(`${pattern}{${repeats}}`, "g") 

This will match any appearance of the pattern cdcdcd.

Unable to cast object of type 'System.DBNull' to type 'System.String`

Convert it Like

string s = System.DBNull.value.ToString();

How to set Meld as git mergetool

You could use complete unix paths like:

PATH=$PATH:/c/python26
git config --global merge.tool meld
git config --global mergetool.meld.path /c/Program files (x86)/meld/bin/meld

This is what is described in "How to get meld working with git on Windows"

Or you can adopt the wrapper approach described in "Use Meld with Git on Windows"

# set up Meld as the default gui diff tool
$ git config --global  diff.guitool meld

# set the path to Meld
$ git config --global mergetool.meld.path C:/meld-1.6.0/Bin/meld.sh

With a script meld.sh:

#!/bin/env bash
C:/Python27/pythonw.exe C:/meld-1.6.0/bin/meld $@

abergmeier mentions in the comments:

I had to do:

git config --global merge.tool meld
git config --global mergetool.meld.path /c/Program files (x86)/Meld/meld/meldc.exe

Note that meldc.exe was especially created to be invoked on Windows via console. Thus meld.exe will not work properly.


CenterOrbit mentions in the comments for Mac OS to install homebrew, and then:

brew cask install meld
git config --global merge.tool meld
git config --global  diff.guitool meld

How to initialize an array in Java?

Try data = new int[] {10,20,30,40,50,60,71,80,90,91 };

Int to Char in C#

(char)myint;

for example:

Console.WriteLine("(char)122 is {0}", (char)122);

yields:

(char)122 is z

How to download excel (.xls) file from API in postman?

Try selecting send and download instead of send when you make the request. (the blue button)

https://www.getpostman.com/docs/responses

"For binary response types, you should select Send and download which will let you save the response to your hard disk. You can then view it using the appropriate viewer."

Disable button after click in JQuery

*Updated

jQuery version would be something like below:

function load(recieving_id){
    $('#roommate_but').prop('disabled', true);
    $.get('include.inc.php?i=' + recieving_id, function(data) {
        $("#roommate_but").html(data);
    });
}

How to get a Docker container's IP address from the host

Add this shell script in your ~/.bashrc or relevant file:

docker-ip() {
  docker inspect --format '{{ .NetworkSettings.IPAddress }}' "$@"
}

Then, to get an IP address of a container, simply do this:

docker-ip YOUR_CONTAINER_ID

For the new version of the Docker, please use the following:

docker-ip() {
        docker inspect --format '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$@"
}

ClassCastException, casting Integer to Double

Changing an integer to a double

int abc=12; //setting up integer "abc"

System.out.println((double)abc); 

The code will output integer "abc" as a double, which means that it will display as "12.0". Notice how there is a decimal place, indicating that this precision digit has been stored.

Same with double if you want to change it back,

double number=13.94;

System.out.println((int)number); 

This code will print on one line, "number" as an integer. The output will be "13". Notice that the value has not been rounded up, the data has actually been omitted.

How to Upload Image file in Retrofit 2

Retrofit 2.0 solution

@Multipart
@POST(APIUtils.UPDATE_PROFILE_IMAGE_URL)
public Call<CommonResponse> requestUpdateImage(@PartMap Map<String, RequestBody> map);

and

    Map<String, RequestBody> params = new HashMap<>();

    params.put("newProfilePicture" + "\"; filename=\"" + FilenameUtils.getName(file.getAbsolutePath()), RequestBody.create(MediaType.parse("image/jpg"), file));



 Call<CommonResponse> call = request.requestUpdateImage(params);

you can use
image/jpg image/png image/gif

Where in memory are my variables stored in C?

pointers(ex:char *arr,int *arr) -------> heap

Nope, they can be on the stack or in the data segment. They can point anywhere.

What EXACTLY is meant by "de-referencing a NULL pointer"?

Dereferencing just means reading the memory value at a given address. So when you have a pointer to something, to dereference the pointer means to read or write the data that the pointer points to.

In C, the unary * operator is the dereferencing operator. If x is a pointer, then *x is what x points to. The unary & operator is the address-of operator. If x is anything, then &x is the address at which x is stored in memory. The * and & operators are inverses of each other: if x is any data, and y is any pointer, then these equations are always true:

*(&x) == x
&(*y) == y

A null pointer is a pointer that does not point to any valid data (but it is not the only such pointer). The C standard says that it is undefined behavior to dereference a null pointer. This means that absolutely anything could happen: the program could crash, it could continue working silently, or it could erase your hard drive (although that's rather unlikely).

In most implementations, you will get a "segmentation fault" or "access violation" if you try to do so, which will almost always result in your program being terminated by the operating system. Here's one way a null pointer could be dereferenced:

int *x = NULL;  // x is a null pointer
int y = *x;     // CRASH: dereference x, trying to read it
*x = 0;         // CRASH: dereference x, trying to write it

And yes, dereferencing a null pointer is pretty much exactly like a NullReferenceException in C# (or a NullPointerException in Java), except that the langauge standard is a little more helpful here. In C#, dereferencing a null reference has well-defined behavior: it always throws a NullReferenceException. There's no way that your program could continue working silently or erase your hard drive like in C (unless there's a bug in the language runtime, but again that's incredibly unlikely as well).

List append() in for loop

You don't need the assignment, list.append(x) will always append x to a and therefore there's no need te redefine a.

a = []
for i in range(5):    
    a.append(i)
print(a)

is all you need. This works because lists are mutable.

Also see the docs on data structures.

How to convert String to DOM Document object in java?

Either escape the double quotes with \

String xmlString = "<element attribname=\"value\" attribname1=\"value1\"> pcdata</element>"

or use single quotes instead

String xmlString = "<element attribname='value' attribname1='value1'> pcdata</element>"

Mail multipart/alternative vs multipart/mixed

Messages have content. Content can be text, html, a DataHandler or a Multipart, and there can only be one content. Multiparts only have BodyParts but can have more than one. BodyParts, like Messages, can have content which has already been described.

A message with HTML, text and an a attachment can be viewed hierarchically like this:

message
  mainMultipart (content for message, subType="mixed")
    ->htmlAndTextBodyPart (bodyPart1 for mainMultipart)
      ->htmlAndTextMultipart (content for htmlAndTextBodyPart, subType="alternative")
        ->textBodyPart (bodyPart2 for the htmlAndTextMultipart)
          ->text (content for textBodyPart)
        ->htmlBodyPart (bodyPart1 for htmlAndTextMultipart)
          ->html (content for htmlBodyPart)
    ->fileBodyPart1 (bodyPart2 for the mainMultipart)
      ->FileDataHandler (content for fileBodyPart1 )

And the code to build such a message:

    // the parent or main part if you will
    Multipart mainMultipart = new MimeMultipart("mixed");

    // this will hold text and html and tells the client there are 2 versions of the message (html and text). presumably text
    // being the alternative to html
    Multipart htmlAndTextMultipart = new MimeMultipart("alternative");

    // set text
    MimeBodyPart textBodyPart = new MimeBodyPart();
    textBodyPart.setText(text);
    htmlAndTextMultipart.addBodyPart(textBodyPart);

    // set html (set this last per rfc1341 which states last = best)
    MimeBodyPart htmlBodyPart = new MimeBodyPart();
    htmlBodyPart.setContent(html, "text/html; charset=utf-8");
    htmlAndTextMultipart.addBodyPart(htmlBodyPart);

    // stuff the multipart into a bodypart and add the bodyPart to the mainMultipart
    MimeBodyPart htmlAndTextBodyPart = new MimeBodyPart();
    htmlAndTextBodyPart.setContent(htmlAndTextMultipart);
    mainMultipart.addBodyPart(htmlAndTextBodyPart);

    // attach file body parts directly to the mainMultipart
    MimeBodyPart filePart = new MimeBodyPart();
    FileDataSource fds = new FileDataSource("/path/to/some/file.txt");
    filePart.setDataHandler(new DataHandler(fds));
    filePart.setFileName(fds.getName());
    mainMultipart.addBodyPart(filePart);

    // set message content
    message.setContent(mainMultipart);

sudo: docker-compose: command not found

Or, just add your binary path into the PATH. At the end of the bashrc:

... 
export PATH=$PATH:/home/user/.local/bin/

save the file and run:

source .bashrc

and the command will work.

What is the maximum length of data I can put in a BLOB column in MySQL?

May or may not be accurate, but according to this site: http://www.htmlite.com/mysql003.php.

BLOB A string with a maximum length of 65535 characters.

The MySQL manual says:

The maximum size of a BLOB or TEXT object is determined by its type, but the largest value you actually can transmit between the client and server is determined by the amount of available memory and the size of the communications buffers

I think the first site gets their answers from interpreting the MySQL manual, per http://dev.mysql.com/doc/refman/5.0/en/storage-requirements.html

How to Set Active Tab in jQuery Ui

Simple jQuery solution - find the <a> element where href="x" and click it:

$('a[href="#tabs-2"]').click();

C/C++ Struct vs Class

It's not possible to define member functions or derive structs from each other in C.

Also, C++ is not only C + "derive structs". Templates, references, user defined namespaces and operator overloading all do not exist in C.

How to create streams from string in Node.Js?

There's a module for that: https://www.npmjs.com/package/string-to-stream

var str = require('string-to-stream')
str('hi there').pipe(process.stdout) // => 'hi there' 

Find if value in column A contains value from column B?

You can use VLOOKUP, but this requires a wrapper function to return True or False. Not to mention it is (relatively) slow. Use COUNTIF or MATCH instead.

Fill down this formula in column K next to the existing values in column I (from I1 to I2691):

=COUNTIF(<entire column E range>,<single column I value>)>0
=COUNTIF($E$1:$E$99504,$I1)>0

You can also use MATCH:

=NOT(ISNA(MATCH(<single column I value>,<entire column E range>)))
=NOT(ISNA(MATCH($I1,$E$1:$E$99504,0)))

Add Facebook Share button to static HTML page

Replace <url> with your own link

<script>function fbs_click() {u=location.href;t=document.title;window.open('http://www.facebook.com/sharer.php?u='+encodeURIComponent(u)+'&t='+encodeURIComponent(t),'sharer','toolbar=0,status=0,width=626,height=436');return false;}</script><style> html .fb_share_link { padding:2px 0 0 20px; height:16px; background:url(http://static.ak.facebook.com/images/share/facebook_share_icon.gif?6:26981) no-repeat top left; }</style><a rel="nofollow" href="http://www.facebook.com/share.php?u=<;url>" onclick="return fbs_click()" target="_blank" class="fb_share_link">Share on Facebook</a>

Classes residing in App_Code is not accessible

make sure that you are using the same namespace as your pages

How to get the current URL within a Django template?

For Django > 3 I do not change settings or anything. I add the below code in the template file.

{{ request.path }}  #  -without GET parameters 
{{ request.get_full_path }}  # - with GET parameters

and in view.py pass request variable to the template file.

view.py:

def view_node_taxon(request, cid):
    showone = get_object_or_404(models.taxon, id = cid)
    context = {'showone':showone,'request':request}
    mytemplate  = loader.get_template('taxon/node.html')
    html = mytemplate.render(context)
    return HttpResponse(html)

Which Java library provides base64 encoding/decoding?

Guava also has Base64 (among other encodings and incredibly useful stuff)

Angular - "has no exported member 'Observable'"

Just remove /Observable from 'rxjs/Observable';

If you then get Cannot find module 'rxjs-compat/Observable' just put below line to thr terminal and press enter.

npm install --save rxjs-compat

Replace CRLF using powershell

Alternative solution that won't append a spurious CR-LF:

$original_file ='C:\Users\abc\Desktop\File\abc.txt'
$text = [IO.File]::ReadAllText($original_file) -replace "`r`n", "`n"
[IO.File]::WriteAllText($original_file, $text)

"Uncaught TypeError: a.indexOf is not a function" error when opening new foundation project

This error is often caused by incompatible jQuery versions. I encountered the same error with a foundation 6 repository. My repository was using jQuery 3, but foundation requires an earlier version. I then changed it and it worked.

If you look at the version of jQuery required by the foundation 5 dependencies it states "jquery": "~2.1.0".

Can you confirm that you are loading the correct version of jQuery?

I hope this helps.

ie8 var w= window.open() - "Message: Invalid argument."

Try remove the last argument. Other than that, make sure urlstring, wname, and wfeatures exist.

Using SVG as background image

Set Background svg with content/cart at center

.login-container {
  justify-content: center;
  align-items: center;
  display: flex;
  height: 100vh; 
  background-image: url(/assets/images/login-bg.svg);
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

Mockito : doAnswer Vs thenReturn

doAnswer and thenReturn do the same thing if:

  1. You are using Mock, not Spy
  2. The method you're stubbing is returning a value, not a void method.

Let's mock this BookService

public interface BookService {
    String getAuthor();
    void queryBookTitle(BookServiceCallback callback);
}

You can stub getAuthor() using doAnswer and thenReturn.

BookService service = mock(BookService.class);
when(service.getAuthor()).thenReturn("Joshua");
// or..
doAnswer(new Answer() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        return "Joshua";
    }
}).when(service).getAuthor();

Note that when using doAnswer, you can't pass a method on when.

// Will throw UnfinishedStubbingException
doAnswer(invocation -> "Joshua").when(service.getAuthor());

So, when would you use doAnswer instead of thenReturn? I can think of two use cases:

  1. When you want to "stub" void method.

Using doAnswer you can do some additionals actions upon method invocation. For example, trigger a callback on queryBookTitle.

BookServiceCallback callback = new BookServiceCallback() {
    @Override
    public void onSuccess(String bookTitle) {
        assertEquals("Effective Java", bookTitle);
    }
};
doAnswer(new Answer() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        BookServiceCallback callback = (BookServiceCallback) invocation.getArguments()[0];
        callback.onSuccess("Effective Java");
        // return null because queryBookTitle is void
        return null;
    }
}).when(service).queryBookTitle(callback);
service.queryBookTitle(callback);
  1. When you are using Spy instead of Mock

When using when-thenReturn on Spy Mockito will call real method and then stub your answer. This can cause a problem if you don't want to call real method, like in this sample:

List list = new LinkedList();
List spy = spy(list);
// Will throw java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
when(spy.get(0)).thenReturn("java");
assertEquals("java", spy.get(0));

Using doAnswer we can stub it safely.

List list = new LinkedList();
List spy = spy(list);
doAnswer(invocation -> "java").when(spy).get(0);
assertEquals("java", spy.get(0));

Actually, if you don't want to do additional actions upon method invocation, you can just use doReturn.

List list = new LinkedList();
List spy = spy(list);
doReturn("java").when(spy).get(0);
assertEquals("java", spy.get(0));

How to show uncommitted changes in Git and some Git diffs in detail

How to show uncommitted changes in Git

The command you are looking for is git diff.

git diff - Show changes between commits, commit and working tree, etc


Here are some of the options it expose which you can use

git diff (no parameters)
Print out differences between your working directory and the index.

git diff --cached:
Print out differences between the index and HEAD (current commit).

git diff HEAD:
Print out differences between your working directory and the HEAD.

git diff --name-only
Show only names of changed files.

git diff --name-status
Show only names and status of changed files.

git diff --color-words
Word by word diff instead of line by line.

Here is a sample of the output for git diff --color-words:

enter image description here


enter image description here

installing vmware tools: location of GCC binary?

First execute this

sudo apt-get install gcc binutils make linux-source

Then run again

/usr/bin/vmware-config-tools.pl

This is all you need to do. Now your system has the gcc make and the linux kernel sources.

Angular2 multiple router-outlet in the same template

Yes you can as said by @tomer above. i want to add some point to @tomer answer.

  • firstly you need to provide name to the router-outlet where you want to load the second routing view in your view. (aux routing angular2.)
  • In angular2 routing few important points are here.

    • path or aux (requires exactly one of these to give the path you have to show as the url).
    • component, loader, redirectTo (requires exactly one of these, which component you want to load on routing)
    • name or as (optional) (requires exactly one of these, the name which specify at the time of routerLink)
    • data (optional, whatever you want to send with the routing that you have to get using routerParams at the receiver end.)

for more info read out here and here.

import {RouteConfig, AuxRoute} from 'angular2/router';
@RouteConfig([
  new AuxRoute({path: '/home', component: HomeCmp})
])
class MyApp {}

NGINX - No input file specified. - php Fast/CGI

server {
    server_name www.test.com test.com;
    access_log /sites/test/logs/access.log;
    error_log /sites/test/logs/error.log;
    root /sites/test;

 location ~ / {

index index.php
    include /etc/nginx/fastcgi_params;
    fastcgi_pass  127.0.0.1:9000;
    fastcgi_index index.php;
    fastcgi_param SCRIPT_FILENAME `$document_root/service/public$fastcgi_script_name`;
}

Python ValueError: too many values to unpack

Iterating over a dictionary object itself actually gives you an iterator over its keys. Python is trying to unpack keys, which you get from m.type + m.purity into (m, k).

My crystal ball says m.type and m.purity are both strings, so your keys are also strings. Strings are iterable, so they can be unpacked; but iterating over the string gives you an iterator over its characters. So whenever m.type + m.purity is more than two characters long, you have too many values to unpack. (And whenever it's shorter, you have too few values to unpack.)

To fix this, you can iterate explicitly over the items of the dict, which are the (key, value) pairs that you seem to be expecting. But if you only want the values, then just use the values.

(In 2.x, itervalues, iterkeys, and iteritems are typically a better idea; the non-iter versions create a new list object containing the values/keys/items. For large dictionaries and trivial tasks within the iteration, this can be a lot slower than the iter versions which just set up an iterator.)

Enable VT-x in your BIOS security settings (refer to documentation for your computer)

Check "Virtualization" status under performance option in your task manager. If you already have enabled it in your BIOS and still status is "Disabled", then go to bios, disable it and save & exit. Restart or shut down again. Enable it in BIOS again and save & exit. This time you'll see the status changed to "Enabled", It took me 3 attempts (don't know why it took that much time, but finally it worked).

The network path was not found

On my end, the problem was an unsuccessful connection to the VPN (while working from home). And yeah, the connectionString was using a context from remote server. Which resulted in the following error:

<Error>
  <Message>An error has occurred.</Message>
  <ExceptionMessage>The network path was not found</ExceptionMessage>
  <ExceptionType>System.ComponentModel.Win32Exception</ExceptionType>
  <StackTrace/>
</Error>

Call Class Method From Another Class

class CurrentValue:

    def __init__(self, value):
        self.value = value

    def set_val(self, k):
        self.value = k

    def get_val(self):
        return self.value


class AddValue:

    def av(self, ocv):
        print('Before:', ocv.get_val())
        num = int(input('Enter number to add : '))
        nnum = num + ocv.get_val()
        ocv.set_val(nnum)
        print('After add :', ocv.get_val())


cvo = CurrentValue(5)

avo = AddValue()

avo.av(cvo)

We define 2 classes, CurrentValue and AddValue We define 3 methods in the first class One init in order to give to the instance variable self.value an initial value A set_val method where we set the self.value to a k A get_val method where we get the valuue of self.value We define one method in the second class A av method where we pass as parameter(ovc) an object of the first class We create an instance (cvo) of the first class We create an instance (avo) of the second class We call the method avo.av(cvo) of the second class and pass as an argument the object we have already created from the first class. So by this way I would like to show how it is possible to call a method of a class from another class.

I am sorry for any inconvenience. This will not happen again.

Before: 5

Enter number to add : 14

After add : 19

How to check if a network port is open on linux?

Just added to mrjandro's solution a quick hack to get rid of simple connection errors / timeouts.

You can adjust the threshold changing max_error_count variable value and add notifications of any sort.

import socket

max_error_count = 10

def increase_error_count():
    # Quick hack to handle false Port not open errors 
    with open('ErrorCount.log') as f:
        for line in f:
            error_count = line
    error_count = int(error_count)
    print "Error counter: " + str(error_count)
    file = open('ErrorCount.log', 'w')
    file.write(str(error_count + 1))
    file.close()
    if error_count == max_error_count:
        # Send email, pushover, slack or do any other fancy stuff
        print "Sending out notification"
        # Reset error counter so it won't flood you with notifications
        file = open('ErrorCount.log', 'w')
        file.write('0')
        file.close()

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2) 
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
        print "Port is open"
else:
        print "Port is not open"
        increase_error_count()

And here you find a Python 3 compatible version (just fixed print syntax):

import socket

max_error_count = 10

def increase_error_count():
    # Quick hack to handle false Port not open errors
    with open('ErrorCount.log') as f:
        for line in f:
            error_count = line
    error_count = int(error_count)
    print ("Error counter: " + str(error_count))
    file = open('ErrorCount.log', 'w')
    file.write(str(error_count + 1))
    file.close()
    if error_count == max_error_count:
        # Send email, pushover, slack or do any other fancy stuff
        print ("Sending out notification")
        # Reset error counter so it won't flood you with notifications
        file = open('ErrorCount.log', 'w')
        file.write('0')
        file.close()

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.settimeout(2) 
result = sock.connect_ex(('127.0.0.1',80))
if result == 0:
        print ("Port is open")
else:
        print ("Port is not open")
        increase_error_count()

Android java.exe finished with non-zero exit value 1

For me this works:

defaultConfig {
    multiDexEnabled true
}

How to find the duration of difference between two dates in java?

   // calculating the difference b/w startDate and endDate
        String startDate = "01-01-2016";
        String endDate = simpleDateFormat.format(currentDate);

        date1 = simpleDateFormat.parse(startDate);
        date2 = simpleDateFormat.parse(endDate);

        long getDiff = date2.getTime() - date1.getTime();

        // using TimeUnit class from java.util.concurrent package
        long getDaysDiff = TimeUnit.MILLISECONDS.toDays(getDiff);

How to calculate difference between two dates in Java

Convert string[] to int[] in one line of code using LINQ

EDIT: to convert to array

int[] asIntegers = arr.Select(s => int.Parse(s)).ToArray();

This should do the trick:

var asIntegers = arr.Select(s => int.Parse(s));

How can I beautify JSON programmatically?

Here's something that might be interesting for developers hacking (minified or obfuscated) JavaScript more frequently.

You can build your own CLI JavaScript beautifier in under 5 mins and have it handy on the command-line. You'll need Mozilla Rhino, JavaScript file of some of the JS beautifiers available online, small hack and a script file to wrap it all up.

I wrote an article explaining the procedure: Command-line JavaScript beautifier implemented in JavaScript.

Node.js - Find home directory in platform agnostic way

Well, it would be more accurate to rely on the feature and not a variable value. Especially as there are 2 possible variables for Windows.

function getUserHome() {
  return process.env.HOME || process.env.USERPROFILE;
}

EDIT: as mentioned in a more recent answer, https://stackoverflow.com/a/32556337/103396 is the right way to go (require('os').homedir()).

How to add a “readonly” attribute to an <input>?

I think "disabled" excludes the input from being sent on the POST

Using Page_Load and Page_PreRender in ASP.Net

The major difference between Page_Load and Page_PreRender is that in the Page_Load method not all of your page controls are completely initialized (loaded), because individual controls Load() methods has not been called yet. This means that tree is not ready for rendering yet. In Page_PreRender you guaranteed that all page controls are loaded and ready for rendering. Technically Page_PreRender is your last chance to tweak the page before it turns into HTML stream.

CSS to select/style first word

I have to disagree with Dale... The strong element is actually the wrong element to use, implying something about the meaning, use, or emphasis of the content while you are simply intending to provide style to the element.

Ideally you would be able to accomplish this with a pseudo-class and your stylesheet, but as that is not possible you should make your markup semantically correct and use <span class="first-word">.

How to access to a child method from the parent in vue.js

Ref and event bus both has issues when your control render is affected by v-if. So, I decided to go with a simpler method.

The idea is using an array as a queue to send methods that needs to be called to the child component. Once the component got mounted, it will process this queue. It watches the queue to execute new methods.

(Borrowing some code from Desmond Lua's answer)

Parent component code:

import ChildComponent from './components/ChildComponent'

new Vue({
  el: '#app',
  data: {
    item: {},
    childMethodsQueue: [],
  },
  template: `
  <div>
     <ChildComponent :item="item" :methods-queue="childMethodsQueue" />
     <button type="submit" @click.prevent="submit">Post</button>
  </div>
  `,
  methods: {
    submit() {
      this.childMethodsQueue.push({name: ChildComponent.methods.save.name, params: {}})
    }
  },
  components: { ChildComponent },
})

This is code for ChildComponent

<template>
 ...
</template>

<script>
export default {
  name: 'ChildComponent',
  props: {
    methodsQueue: { type: Array },
  },
  watch: {
    methodsQueue: function () {
      this.processMethodsQueue()
    },
  },
  mounted() {
    this.processMethodsQueue()
  },
  methods: {
    save() {
        console.log("Child saved...")
    },
    processMethodsQueue() {
      if (!this.methodsQueue) return
      let len = this.methodsQueue.length
      for (let i = 0; i < len; i++) {
        let method = this.methodsQueue.shift()
        this[method.name](method.params)
      }
    },
  },
}
</script>

And there is a lot of room for improvement like moving processMethodsQueue to a mixin...

How can I print to the same line?

In Linux, there is different escape sequences for control terminal. For example, there is special escape sequence for erase whole line: \33[2K and for move cursor to previous line: \33[1A. So all you need is to print this every time you need to refresh the line. Here is the code which prints Line 1 (second variant):

System.out.println("Line 1 (first variant)");
System.out.print("\33[1A\33[2K");
System.out.println("Line 1 (second variant)");

There are codes for cursor navigation, clearing screen and so on.

I think there are some libraries which helps with it (ncurses?).

Property [title] does not exist on this collection instance

When you're using get() you get a collection. In this case you need to iterate over it to get properties:

@foreach ($collection as $object)
    {{ $object->title }}
@endforeach

Or you could just get one of objects by it's index:

{{ $collection[0]->title }}

Or get first object from collection:

{{ $collection->first() }}

When you're using find() or first() you get an object, so you can get properties with simple:

{{ $object->title }}

Is there a difference between `continue` and `pass` in a for loop in python?

Yes, there is a difference. Continue actually skips the rest of the current iteration of the loop (returning to the beginning). Pass is a blank statement that does nothing.

See the python docs

How do I make the return type of a method generic?

You have to convert the type of your return value of the method to the Generic type which you pass to the method during calling.

    public static T values<T>()
    {
        Random random = new Random();
        int number = random.Next(1, 4);
        return (T)Convert.ChangeType(number, typeof(T));
    }

You need pass a type that is type casteable for the value you return through that method.

If you would want to return a value which is not type casteable to the generic type you pass, you might have to alter the code or make sure you pass a type that is casteable for the return value of method. So, this approach is not reccomended.

How do I convert an integer to binary in JavaScript?

This is my code:

var x = prompt("enter number", "7");
var i = 0;
var binaryvar = " ";

function add(n) {
    if (n == 0) {
        binaryvar = "0" + binaryvar; 
    }
    else {
        binaryvar = "1" + binaryvar;
    }
}

function binary() {
    while (i < 1) {
        if (x == 1) {
            add(1);
            document.write(binaryvar);
            break;
        }
        else {
            if (x % 2 == 0) {
                x = x / 2;
                add(0);
            }
            else {
                x = (x - 1) / 2;
                add(1);
            }
        }
    }
}

binary();

How do I implement onchange of <input type="text"> with jQuery?

You could simply work with the id

$("#your_id").on("change",function() {
    alert(this.value);
});

Read line by line in bash script

The correct version of your script is as follows;

FILE="cat test"
$FILE | \
while read CMD; do
echo $CMD
done

However this kind of indirection --putting your command in a variable named FILE-- is unnecessary. Use one of the solutions already provided. I just wanted to point out your mistake.

How to open a link in new tab (chrome) using Selenium WebDriver?

You can open multiple browser or a window by using below code:

WebDriver driver = new ChromeDriver();
driver.get("http://yahoo.com");  

WebDriver driver1 = new ChromeDriver();
driver1.get("google.com");

WebDriver driver2 = new InternetExplorerDriver();
driver2.get("google.com/gmap");

jquery - return value using ajax result on success

Hi try async:false in your ajax call..

How can I create keystore from an existing certificate (abc.crt) and abc.key files?

If the keystore is for tomcat then, after creating the keystore with the above answers, you must add a final step to create the "tomcat" alias for the key:

keytool -changealias -alias "1" -destalias "tomcat" -keystore keystore-file.jks

You can check the result with:

keytool -list -keystore keystore-file.jks -v

Razor Views not seeing System.Web.Mvc.HtmlHelper

Just started looking into the issue myself and this is what it look like in my case. If you have the correct values in your web config then Its just a bug in MVC4. http://connect.microsoft.com/VisualStudio/feedback/details/727729/viewbag-not-recognized-in-asp-net-mvc-4-project

Catching errors in Angular HttpClient

Fairly straightforward (in compared to how it was done with the previous API).

Source from (copy and pasted) the Angular official guide

 http
  .get<ItemsResponse>('/api/items')
  .subscribe(
    // Successful responses call the first callback.
    data => {...},
    // Errors will call this callback instead:
    err => {
      console.log('Something went wrong!');
    }
  );

How to get a Char from an ASCII Character Code in c#

You can simply write:

char c = (char) 2;

or

char c = Convert.ToChar(2);

or more complex option for ASCII encoding only

char[] characters = System.Text.Encoding.ASCII.GetChars(new byte[]{2});
char c = characters[0];

Rails Root directory path?

For super correctness, you should use:

Rails.root.join('foo','bar')

which will allow your app to work on platforms where / is not the directory separator, should anyone try and run it on one.

How to access host port from docker container

We found that a simpler solution to all this networking junk is to just use the domain socket for the service. If you're trying to connect to the host anyway, just mount the socket as a volume, and you're on your way. For postgresql, this was as simple as:

docker run -v /var/run/postgresql:/var/run/postgresql

Then we just set up our database connection to use the socket instead of network. Literally that easy.